Plasma activated conformal dielectric film deposition

ABSTRACT

Methods of depositing a film on a substrate surface include surface mediated reactions in which a film is grown over one or more cycles of reactant adsorption and reaction. In one aspect, the method is characterized by intermittent delivery of dopant species to the film between the cycles of adsorption and reaction.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims priority to U.S.application Ser. No. 14/607,997 (to be issued as U.S. Pat. No.9,570,274), titled “PLASMA ACTIVATED CONFORMAL DIELECTRIC FILMDEPOSITION,” filed Jan. 28, 2015, which is a continuation of U.S.application Ser. No. 14/133,239 (now U.S. Pat. No. 8,999,859), titled“PLASMA ACTIVATED CONFORMAL DIELECTRIC FILM DEPOSITION,” filed Dec. 18,2013, which is a divisional of U.S. patent application Ser. No.13/242,084 (now U.S. Pat. No. 8,637,411), titled “PLASMA ACTIVATEDCONFORMAL DIELECTRIC FILM DEPOSITION,” filed on Sep. 23, 2011, which isa continuation-in-part of U.S. patent application Ser. No. 13/084,399(now U.S. Pat. No. 8,728,956), titled “PLASMA ACTIVATED CONFORMAL FILMDEPOSITION,” filed Apr. 11, 2011, which claims priority to the followingU.S. Provisional Patent Applications: No. 61/324,710, filed Apr. 15,2010, No. 61/372,367, filed Aug. 10, 2010, No. 61/379,081, filed Sep. 1,2010, and No. 61/417,807, filed Nov. 29, 2010. U.S. patent applicationSer. No. 13/242,084 is also a continuation-in-part of U.S. patentapplication Ser. No. 13/084,305 (now abandoned), titled “SILICON NITRIDEFILMS AND METHODS,” filed Apr. 11, 2011. Each of the above patentapplications is hereby incorporated by reference in its entirety and forall purposes.

BACKGROUND

Various thin film layers for semiconductor devices may be deposited withatomic layer deposition (ALD) processes. However, existing ALD processesmay not be suitable for depositing highly conformal dielectric films.

SUMMARY

Various aspects disclosed herein pertain to methods and apparatus fordepositing a film on a substrate surface. In certain embodiments, themethods include depositing a film by surface mediated reactions in whichthe film is grown over one or more cycles of reactant adsorption andreaction. In one aspect, the method is characterized by intermittentdelivery of dopant species to the film between the cycles of adsorptionand reaction. At some point, the dopant species may be driven across thesubstrate surface to dope regions of the substrate.

In one aspect, a disclosed method deposits a film on a substrate surfacein a reaction chamber. The method may be characterized by the followingoperations: (a) introducing a first reactant into the reaction chamberunder conditions allowing the first reactant to adsorb onto thesubstrate surface; (b) introducing a second reactant into the reactionchamber while the first reactant is adsorbed on the substrate surface;(c) exposing the substrate surface to plasma to drive a reaction betweenthe first and second reactants on the substrate surface to form aportion of the film; (d) repeating (a)-(c) at least once; (e)introducing a dopant containing material, not introduced during (a)-(d),into the reaction chamber under conditions allowing the dopantcontaining material to contact an exposed surface of the film; and (f)introducing a dopant into the film from the dopant containing material.Introducing the dopant into the film may involve exposing the dopantcontaining material to a plasma.

In various implementations, the method additionally includes driving thedopant from the film into features of the substrate surface on which thefilm resides. Driving the dopant from the film may be accomplished byannealing the film. In some applications, the film resides on athree-dimensional feature of the substrate surface and driving thedopant from the film provides conformal diffusion of the dopant into thefeature. In a specific application, the feature has a width of notgreater than about 40 nanometers.

In certain implementations, the film is a dielectric film. In somecases, the total film thickness is between about 10-100 Angstroms. Invarious embodiments, the concentration of dopant in the film is betweenabout 0.01 and 10 percent by weight.

In certain embodiments, the method of this aspect additionally includesrepeating (a)-(c) after (e) or (f). In certain embodiments, the methodof this aspect additionally includes repeating (a)-(e). In someimplementations, the amount of film deposited during (a)-(c) is betweenabout 0.5 to 1 Angstroms.

In certain embodiments, the method additionally includes purging thesecond reactant from the reaction chamber prior to exposing thesubstrate surface to plasma. The purging may be accomplished by flowinga gas containing an oxidant into the reaction chamber. In someimplementations, the first and second reactants co-exist in vapor phasein the reaction chamber and the first and second reactants do notappreciably react with one another in the reaction chamber untilexposure to plasma in (c).

In certain embodiments, the first reactant is an oxidizing agent, e.g.,nitrous oxide. In certain embodiments, the second reactant is adielectric precursor such as (i) an alkylamino silane(SiH_(x)(NR₂)_(4−x)), where x=1-3, and R includes alkyl groups, or (ii)a halosilane (SiH_(x)Y_(4−x)), where x=1-3, and Y includes Cl, Br, andI). In a specific embodiment, the second reactant is BTBAS. In certainembodiments, the dopant containing material is phosphine, arsine, analkylborane, an alkyl gallane, an alkylphosphine, a phosphorus halide,an arsenic halide, a gallium halide, a boron halide, an alkylborane, ordiborane.

In another aspect, a disclosed method deposits a dielectric film on asubstrate surface in a reaction chamber. This method may becharacterized by the following operations: (a) flowing an oxidant intothe reaction chamber under conditions allowing the first reactant toadsorb onto the substrate surface; (b) introducing a dielectricprecursor into the reaction chamber while the oxidant continues to flowinto the reaction chamber; (c) exposing the substrate surface to plasmato drive a reaction between the dielectric precursor and oxidant on thesubstrate surface to form a portion of the dielectric film; (d)introducing a dopant containing material, not introduced during (a)-(c),into the reaction chamber under conditions allowing the dopantcontaining material to contact an exposed surface of the film; and (e)causing a dopant from the containing material to integrate into thedielectric film. In one implementation, the dielectric precursor isBTBAS or another precursor as identified in the prior aspect.

Further, the method may require that operations (a)-(c) be repeated oneor more times. In a specific example, the oxidant contains a first ratioof oxygen to nitrogen when (a) is initially performed but the oxidantcontains a second ratio of oxygen to nitrogen when (a) is subsequentlyperformed. The second ratio is smaller than the first ratio. Forexample, the oxidant may contain elemental oxygen when (a) is initiallyperformed but contain nitrous oxide when (a) is repeated. In someembodiments, the substrate is at a first temperature when (c) isinitially performed, and the substrate is at a second temperature, whichis higher than the first temperature, when (c) is repeated.

In some cases, the method further includes driving the dopant from thedielectric film into the substrate. In some embodiments, the methodfurther includes contacting the substrate surface with the dopantcontaining material prior to (a).

In another aspect, a disclosed method deposits a dielectric film on asubstrate surface in a reaction chamber according to the followingoperations: (a) introducing a dielectric precursor into the reactionchamber under conditions allowing the precursor to adsorb onto thesubstrate surface; (b) thereafter purging the dielectric precursor fromthe reaction chamber while the precursor remains adsorbed on thesubstrate surface; (c) exposing the substrate surface to plasma to drivea reaction of the dielectric precursor on the substrate surface to forma portion of the dielectric film; and (d) introducing a dopantprecursor, not introduced during (a)-(c), into the reaction chamberunder conditions allowing the dopant precursor to contact the portion ofthe dielectric film. In some implementations, the method additionallyinvolves flowing an oxidant into the reaction chamber prior to andduring (a)-(c). In some cases, the method additionally involves reactingthe dopant precursor to incorporate a dopant into the film.

Yet another aspect concerns an apparatus for depositing a doped film ona substrate surface. The apparatus may be characterized by the followingfeatures: a reaction chamber comprising a device for holding thesubstrate during deposition of the doped dielectric film; one or moreprocess gas inlets coupled to the reaction chamber; and a controller.The controller is designed or configured to cause the apparatus toperform the following operations: (a) introducing a first reactant intothe reaction chamber under conditions allowing the first reactant toadsorb onto the substrate surface; (b) introducing a second reactantinto the reaction chamber while the first reactant is adsorbed on thesubstrate surface; (c) exposing the substrate surface to plasma to drivea reaction between the first and second reactants on the substratesurface to form a portion of the film; (d) repeating (a)-(c) at leastonce; (e) introducing a dopant containing material, not introducedduring (a)-(d), into the reaction chamber under conditions allowing thedopant containing material to contact an exposed surface of the film;and (f) introducing a dopant into the film from the dopant containingmaterial. The controller may be designed or configured to directperformance of other methods such as those discussed in accordance withother aspects.

In certain embodiments, the controller is further designed or configuredto cause the apparatus to flow an oxidant into the reaction chamberprior to and during (a)-(d). In certain embodiments, the controller isfurther designed or configured to cause repeating (a)-(c) after (e) or(f). In certain embodiments, the controller is further designed orconfigured to cause driving the dopant from the film into features ofthe substrate surface on which the film resides. Driving the dopant fromthe film may be accomplished by annealing the film. In someimplementations, the controller is further designed or configured tocause (e) to be performed at intervals between one or more repetitionsof (a)-(d) and wherein said intervals are varied over the course ofdepositing the film.

In various implementations, the controller is further designed orconfigured to cause purging the second reactant from the reactionchamber prior to exposing the substrate surface to plasma. In oneexample, purging is accomplished by flowing a gas comprising an oxidantinto the reaction chamber under the direction of the controller.

These and other features will be described in more detail below withreference to the associated drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows a timing diagram for an example conformalfilm deposition (CFD) process according to an embodiment of the presentdisclosure.

FIG. 2 schematically shows a timing diagram for another example CFDprocess according to an embodiment of the present disclosure.

FIG. 3 schematically shows a timing diagram for another example CFDprocess according to an embodiment of the present disclosure.

FIG. 4 schematically shows a timing diagram for an example CFD processincluding a plasma treatment cycle according to an embodiment of thepresent disclosure.

FIG. 5 shows an example correlation between a wet etch rate ratio and adeposition temperature for films deposited according to an embodiment ofthe present disclosure.

FIG. 6 shows an example correlation between a wet etch rate ratio and afilm stress for films deposited according to an embodiment the presentdisclosure.

FIG. 7 shows an example correlation between film contaminantconcentration and deposition temperature for films deposited accordingto an embodiment of the present disclosure.

FIG. 8 schematically shows an example cross-section of a non-planarsubstrate comprising a plurality of gaps.

FIG. 9 schematically shows a timing diagram for an example CFD processincluding a transition to a PECVD process according to an embodiment ofthe present disclosure.

FIG. 10 schematically shows an example cross-section of a gap fillincluding a keyhole void.

FIG. 11 schematically shows a timing diagram for an example CFD processincluding an in-situ etch according to an embodiment of the presentdisclosure.

FIG. 12A schematically shows an example cross-section of a re-entrantgap fill profile.

FIG. 12B schematically shows an example cross-section of the re-entrantgap fill profile of FIG. 12A during an in-situ etch process according toan embodiment of the present disclosure.

FIG. 12C schematically shows an example cross-section of the gap fillprofile of FIG. 12B during a deposition process after an in-situ etchaccording to an embodiment of the present disclosure.

FIG. 13 schematically shows an example process station according to anembodiment of the present disclosure.

FIG. 14 schematically shows an example process tool including aplurality of process stations and a controller according to anembodiment of the present disclosure.

FIG. 15 schematically shows an example cross-sectional view of athrough-silicon via during a CFD process including an in-situ etchaccording to an embodiment of the present disclosure.

FIG. 16 illustrates a transistor having a three-dimensional gatestructure, in which the source and drain are formed in thin verticalstructures that are difficult to dope by conventional ion implantationtechniques.

FIG. 17 presents a baseline CFD sequence of operations from left toright with advancing time along the x axis.

FIGS. 18 and 19 depict embodiments in which dopant is deposited at theinterface with the underlying substrate, followed by CFD cyclesinterspersed with a dopant delivery, and optionally topped off with anundoped protective “capping” layer may be a CFD oxide film.

FIG. 20 shows a typical deposition block used to synthesize a CFDBSG/PSG film.

FIG. 21 shows step coverage for CFD films calculated to be ˜100% ondense and isolated structures.

FIG. 22 presents SIMS data showing that the average boron concentrationin CFD films can be tuned in a range of about 0.5-3.5 wt % boron.

DETAILED DESCRIPTION

Manufacture of semiconductor devices typically involves depositing oneor more thin films on a non-planar substrate in an integratedfabrication process. In some aspects of the integrated process it may beuseful to deposit thin films that conform to substrate topography. Forexample, a silicon nitride film may be deposited on top of an elevatedgate stack to act as a spacer layer for protecting lightly-doped sourceand drain regions from subsequent ion implantation processes.

In spacer layer deposition processes, chemical vapor deposition (CVD)processes may be used to form a silicon nitride film on the non-planarsubstrate, which is then anisotropically etched to form the spacerstructure. However, as a distance between gate stacks decreases, masstransport limitations of CVD gas phase reactions may cause“bread-loafing” deposition effects. Such effects typically exhibitthicker deposition at top surfaces of gate stacks and thinner depositionat the bottom corners of gate stacks. Further, because some die may haveregions of differing device density, mass transport effects across thewafer surface may result in within-die and within-wafer film thicknessvariation. These thickness variations may result in over-etching of someregions and under-etching of other regions. This may degrade deviceperformance and/or die yield.

Some approaches to addressing these issues involve atomic layerdeposition (ALD). In contrast with a CVD process, where thermallyactivated gas phase reactions are used to deposit films, ALD processesuse surface-mediated deposition reactions to deposit films on alayer-by-layer basis. In one example ALD process, a substrate surface,including a population of surface active sites, is exposed to a gasphase distribution of a first film precursor (P1). Some molecules of P1may form a condensed phase atop the substrate surface, includingchemisorbed species and physisorbed molecules of P1. The reactor is thenevacuated to remove gas phase and physisorbed P1 so that onlychemisorbed species remain. A second film precursor (P2) is thenintroduced to the reactor so that some molecules of P2 adsorb to thesubstrate surface. The reactor may again be evacuated, this time toremove unbound P2. Subsequently, thermal energy provided to thesubstrate activates surface reactions between adsorbed molecules of P1and P2, forming a film layer. Finally, the reactor is evacuated toremove reaction by-products and possibly unreacted P1 and P2, ending theALD cycle. Additional ALD cycles may be included to build filmthickness.

Depending on the exposure time of the precursor dosing steps and thesticking coefficients of the precursors, each ALD cycle may deposit afilm layer of, in one example, between one-half and three angstromsthick. Thus, ALD processes may be time consuming when depositing filmsmore than a few nanometers thick. Further, some precursors may have longexposure times to deposit a conformal film, which may also reduce waferthroughput time.

Conformal films may also be deposited on planar substrates. For example,antireflective layers for lithographic patterning applications may beformed from planar stacks comprising alternating film types. Suchantireflective layers may be approximately 100 to 1000 angstroms thick,making ALD processes less attractive than CVD processes. However, suchanti-reflective layers may also have a lower tolerance for within-waferthickness variation than many CVD processes may provide. For example, a600-angstrom thick antireflective layer may tolerate a thickness rangeof less than 3 angstroms.

Accordingly, various embodiments are provided herein providing processesand equipment for plasma-activated conformal film deposition (CFD) onnon-planar and planar substrates. These embodiments incorporate variousfeatures employed in some but not all CFD processes. Among thesefeatures are (1) eliminating or reducing the time required to “sweep”one or both reactants from the reaction chamber, (2) providing acontinuous flow of at least one reactant while a different reactant isintermittently flowed into the reaction chamber, (3) igniting plasmawhile one of the reactants is present in the gas phase, rather than whenall reactants are cleared from the reaction chamber, (4) treatingdeposited CFD films with a plasma to modify the film properties, (5)depositing a portion of a film by PECVD after depositing a first portionof the film by CFD, typically in the same reaction chamber, (6) etchinga partially deposited film between CFD stages, and (7) doping the CFDfilm by interspersing dopant delivery cycles with film only depositioncycles. Of course, this list is not exhaustive. Various other CFDfeatures will be apparent when considering the remainder of thespecification.

The concept of a CFD “cycle” is relevant to the discussion of variousembodiments herein. Generally a cycle is the minimum set of operationsrequired to perform a surface deposition reaction one time. The resultof one cycle is production of at least a partial film layer on asubstrate surface. Typically, a CFD cycle will include only those stepsnecessary to deliver and adsorb each reactant to the substrate surface,and then react those adsorbed reactants to form the partial layer offilm. Of course, the cycle may include certain ancillary steps such assweeping one of the reactants or byproducts and/or treating the partialfilm as deposited. Generally, a cycle contains only one instance of aunique sequence of operations. As an example, a cycle may include thefollowing operations: (i) delivery/adsorption of reactant A, (ii)delivery/adsorption of reactant B, (iii) sweep B out of the reactionchamber, and (iv) apply plasma to drive a surface reaction of A and B toform the partial film layer on the surface.

The seven above-mentioned features will now be discussed further. In thefollowing descriptions, consider a CFD reaction in which one morereactants adsorb to the substrate surface and then react to form a filmon the surface by interaction with plasma.

Feature 1 (Continuous Flow of a Reactant)—Reactant A continues to flowto a reaction chamber during one or more portions of a CFD cycle whenthe reactant would not normally flow in conventional ALD. Inconventional ALD, reactant A flows only for the purpose of having thereactant adsorb onto the substrate surface. At other phases of an ALDcycle, reactant A does not flow. In accordance with certain CFDembodiments described herein, however, reactant A flows not only duringphases associated with its adsorption but also during phases of a CFDcycle that perform operations other than adsorption of A. For example,in many embodiments, reactant A flows into the reactor while theapparatus is dosing a second reactant (reactant B herein). Thus, duringat least a portion of a CFD cycle, reactants A and B coexist in the gasphase. Further, reactant A may flow while plasma is applied to drive areaction at the substrate surface. Note that the continuously flowingreactant may be delivered to the reaction chamber in conjunction with acarrier gas—e.g., argon.

One advantage of the continuous flow embodiment is that the establishedflow avoids the delays and flow variations caused by transientinitialization and stabilization of flow associated with turning theflow on and off.

As a specific example, an oxide film may be deposited by a conformalfilm deposition process using a principal reactant (sometimes referredto as a “solid component” precursor or, in this example, simply“reactant B”). Bis(tert-butylamino)silane (BTBAS) is one such principalreactant. In this example, the oxide deposition process involvesdelivery of an oxidant such as oxygen or nitrous oxide, which flowsinitially and continuously during delivery of the principal reactant indistinct exposure phases. The oxidant also continues to flow duringdistinct plasma exposure phases. See for example the sequence depictedin FIG. 1. For comparison, in a conventional ALD process, the flow ofoxidant would stop when the solid component precursor is delivered tothe reactor. For example, the flow of reactant A would stop whenreactant B is delivered.

In some specific examples, the reactant that flows continuously is an“auxiliary” reactant. As used herein, an “auxiliary” reactant is anyreactant that is not a principal reactant. As suggested above, aprincipal reactant contains an element that is solid at roomtemperature, which element is contributed to the film formed by CFD.Examples of such elements are metals (e.g., aluminum and titanium),semiconductors (e.g., silicon and germanium), and non-metals ormetalloids (e.g., boron). Examples of auxiliary reactants includeoxygen, ozone, hydrogen, carbon monoxide, nitrous oxide, ammonia, alkylamines, and the like.

The continuously flowing reactant may be provided at a constant flowrate or at varied but controlled flow rate. In the latter case, as anexample, the flow rate of an auxiliary reactant may drop during anexposure phase when the primary reactant is delivered. For example, inoxide deposition, the oxidant (e.g., oxygen or nitrous oxide) may flowcontinuously during the entire deposition sequence, but its flow ratemay drop when the primary reactant (e.g., BTBAS) is delivered. Thisincreases the partial pressure of BTBAS during its dosing, therebyreducing the exposure time needed to saturate the substrate surface.Shortly before igniting the plasma, the flow of oxidant may be increasedto reduce the likelihood that BTBAS is present during the plasmaexposure phase. In some embodiments, the continuously flowing reactantflows at a varied flow rate over the course of two or more depositioncycles. For example, the reactant may flow at a first flow rate during afirst CFD cycle and at a second flow rate during a second CFD cycle.

When multiple reactants are employed and the flow of one of them iscontinuous, at least two of them will co-exist in the gas phase during aportion of the CFD cycle. Similarly, when no purge step is performedafter delivery of the first reactant, two reactants will co-exist.Therefore, it may be important to employ reactants that do notappreciably react with one another in the gas phase absent applicationof activation energy. Typically, the reactants should not react untilpresent on the substrate surface and exposed to plasma or anotherappropriate non-thermal activation condition. Choosing such reactantsinvolves considerations of at least (1) the thermodynamic favorability(Gibb's free energy <0) of the desired reaction, and (2) the activationenergy for the reaction, which should be sufficiently great so thatthere is negligible reaction at the desired deposition temperature.

Feature 2 (Reduce or Eliminate a Sweep Step)—In certain embodiments, theprocess dispenses with or reduces the time associated with a sweep stepthat would normally be performed in conventional ALD. In conventionalALD, a separate sweep step is performed after each reactant is deliveredand adsorbed onto the substrate surface. Little or no adsorption orreaction occurs in a conventional ALD sweep step. In a CFD cycle, thesweep step is reduced or eliminated after delivery of at least one ofthe reactants. An example of a process sequence in which a sweep step isremoved is presented in FIG. 1. No sweep step is performed to sweepreactant A from the reaction chamber. In some cases, no sweep step isperformed after delivery of the first reactant in a CFD cycle but asweep step is optionally performed after delivery of the second or lastdelivered reactant.

The concept of a CFD “sweep” step or phase appears in the discussionvarious embodiments herein. Generally, a sweep phase removes or purgesone of the vapor phase reactant from a reaction chamber and typicallyoccurs only after delivery of such reactant is completed. In otherwords, that reactant is no longer delivered to the reaction chamberduring sweep phase. However, the reactant remains adsorbed on thesubstrate surface during the sweep phase. Typically, the sweep serves toremove any residual vapor phase reactant in the chamber after thereactant is adsorbed on the substrate surface to the desired level. Asweep phase may also remove weakly adsorbed species (e.g., certainprecursor ligands or reaction by-products) from the substrate surface.In ALD, the sweep phase has been viewed as necessary to prevent gasphase interaction of two reactants or interaction of one reactant with athermal, plasma or other driving force for the surface reaction. Ingeneral, and unless otherwise specified herein, a sweep phase may beaccomplished by (i) evacuating a reaction chamber, and/or (ii) flowinggas not containing the species to be swept out through the reactionchamber. In the case of (ii), such gas may be, for example, an inert gasor an auxiliary reactant such as a continuously flowing auxiliaryreactant.

Elimination of the sweep phase may be accomplished with or withoutcontinuous flow of the other reactant. In the embodiment depicted inFIG. 1, reactant A is not swept away but rather continues to flow afterits adsorption onto the substrate surface is completed (illustrated byreference number 130 in the figure).

In various embodiments where two or more reactants are employed, thereactant which has its sweep step eliminated or reduced is an auxiliaryreactant. As an example, auxiliary reactant is an oxidant or a nitrogensource and the primary reactant is a silicon, boron, or germaniumcontaining precursor. Of course, a sweep of the principal reactant mayalso be reduced or eliminated. In some examples, no sweep step isperformed after delivery of an auxiliary reactant but a sweep step isoptionally performed after delivery of a principal reactant.

As mentioned, the sweep phase need not be fully eliminated but simplyreduced in duration in comparison to sweep phases in conventional ALDprocesses. For example, the sweep phase of a reactant such as anauxiliary reactant during a CFD cycle may be performed for about 0.2seconds or less, e.g., for about 0.001 to 0.1 seconds.

Feature 3 (Igniting Plasma while One of the Reactants is Present in theGas Phase)—With this feature, a plasma is ignited before all reactantshave been cleared from the reaction chamber. This is contrary toconventional ALD, where the plasma activation or other reaction drivingoperation is provided only after the vapor phase reactants are no longerpresent in the reaction chamber. Note that this feature wouldnecessarily occur when reactant A flows continuously during the plasmaportion of a CFD cycle as depicted in FIG. 1. However, the disclosedembodiments are not limited in this manner. One or more reactants mayflow during the plasma phase of a CFD cycle but need not flowcontinuously during a CFD cycle. Further, the reactant present in vaporphase during plasma activation may be a principal reactant or anauxiliary reactant (when two more reactants are employed in a CFDcycle).

For example, a sequence might be (i) introduce reactant A, (ii) purge A,(iii) introduce reactant B and while B is flowing strike a plasma, and(iv) purge. In such embodiments, the process employs a plasma activatedreactant species from the gas phase. This is a general example where CFDis not constrained to a sequence of sequential steps.

If the activation plasma is provided during the time when the solidcomponent precursor (primary reactant) is supplied to the reactor, thestep coverage may become less conformal, but the deposition rate willtypically increase. However if plasma activation occurs only duringdelivery of one an auxiliary reactant this is not necessarily the case.The plasma can activate the vapor phase auxiliary component to render itmore reactive and thereby increase its reactivity in the conformal filmdeposition reaction. In certain embodiments, this feature is employedwhen depositing a silicon containing film such as an oxide, nitride, orcarbide.

Feature 4 (Plasma Treatment of Deposited CFD Films)—In theseembodiments, the plasma may serve two or more roles in the conformalfilm deposition process. One of its roles is to activate or drive thefilm formation reaction during each CFD cycle. Its other role is totreat the film after the CFD film has been partially or fully depositedfollowing one or more CFD cycles. The plasma treatment is intended tomodify one or more film properties. Typically, though not necessarily,the plasma treatment phase is conducted under conditions that aredifferent from those employed to activate the film formation reaction(i.e., to drive the film formation reaction). As an example, the plasmatreatment may be performed in the presence of a reducing or oxidizingenvironment (e.g., in the presence of hydrogen or oxygen), while thisneed not be the case during the activation portion of a CFD cycle.

The plasma treatment operation may be performed during every cycle ofthe CFD process, during every other cycle, or on some less frequentbasis. The treatment may be performed on regular intervals, tied to afixed number of CFD cycles, or it may be performed variably (e.g., atvarying intervals of CFD cycles) or even randomly. In a typical example,film deposition is performed for a few CFD cycles, to reach appropriatefilm thickness, and then the plasma treatment is employed. Thereafter,film deposition is again performed for a number of CFD cycles withoutplasma treatment before the treatment is again performed. Thissuper-sequence of x number of CFD cycles, followed by plasma treatment(film modification) may be repeated until the film is completely formedby CFD.

In certain embodiments, the plasma treatment may be performed beforeinitiation of CFD cycling to modify one or more properties of thesurface on which the CFD film is deposited. In various embodiments, thesurface is made from silicon (doped or undoped) or a silicon containingmaterial. The modified surface may be better able to produce a highquality interface with the subsequently deposited CFD film. Theinterface may provide, e.g., good adhesion, reliable electricalproperties through, e.g., defect reduction, etc.

The pretreatment of the substrate prior to CFD is not limited to anyparticular plasma treatment. In certain embodiments, the pre-treatmentinvolves exposure to hydrogen-plasma, nitrogen-plasma,nitrogen/hydrogen-plasma, ammonia-plasma, argon-plasma, helium-plasma,helium anneal, hydrogen-anneal, ammonia-anneal, and UV-cure in thepresence of helium, hydrogen, argon, nitrogen, hydrogen/nitrogen-forminggas, and/or ammonia. Plasma processing may be enabled with variousplasma generators including, though not limited to, microwave,ICP-remote, direct and others known to those in the art.

Overall, the treatment may occur before, during and after CFD cycling.When occurring during CFD cycling, the frequency of treatment may bechosen for the appropriate deposition conditions. Typically, thetreatment will occur not more often than once per cycle.

As an example, consider a process for forming silicon nitride fromprecursors having some carbon present. Examples of such precursorsinclude BTBAS. As a consequence of the carbon present in the precursor,the as deposited nitride film includes some carbon impurity, which maydegrade the electrical properties of the nitride. To counteract thisproblem, after a few CFD cycles with the carbon-containing precursor,the partially deposited film is exposed to hydrogen in the presence ofplasma to reduce and ultimately remove the carbon impurity.

The plasma conditions employed to modify the film surface may be chosento effect a desired change in film properties and/or composition. Amongthe plasma conditions that can be selected and/or tailored for thedesired modification are oxidizing conditions, reducing conditions,etching conditions, power used to generate the plasma, frequency used togenerate the plasma, use of two or more frequencies to generate theplasma, plasma density, the distance between the plasma and thesubstrate, etc. Examples of CFD film properties that can be modified byplasma treatment include, internal film stress, etch resistance,density, hardness, optical properties (refractive index, reflectivity,optical density, etc.), dielectric constant, carbon content, electricalproperties (Vfb spread, etc.), and the like.

In some embodiments, a treatment other than a plasma treatment isemployed to modify the properties of the as deposited film. Suchtreatments include electromagnetic radiation treatments, thermaltreatments (e.g., anneals or high temperature pulses), and the like. Anyof these treatments may be performed alone or in combination withanother treatment, including a plasma treatment. Any such treatment canbe employed as a substitute for any of the above-described plasmatreatments. In a specific embodiment, the treatment involves exposingthe film to ultraviolet radiation. As described below, in a specificembodiment, the method involves the application of UV-radiation to anoxide CFD film in situ (i.e., during formation of the film) or postdeposition of the oxide. Such treatment serves to reduce or eliminatedefect structure and provide improved electrical performance.

In certain specific embodiments, a UV treatment can be coupled with aplasma treatment. These two operations can be performed concurrently orsequentially. In the sequential option, the UV operation optionallytakes place first. In the concurrent option, the two treatments may beprovided from separate sources (e.g., an RF power source for the plasmaand a lamp for the UV) or from a single source such as a helium plasmathat produces UV radiation as a byproduct.

Feature 5 (Depositing by CFD and then Transitioning to PECVD)—In suchembodiments, the completed film is generated in part by CFD and in partby a CVD process such as PECVD. Typically, the CFD portion of thedeposition process if performed first and the PECVD portion is performedsecond, although this need not be the case. Mixed CFD/CVD processes canimprove the step coverage over that seen with CVD alone and additionallyimprove the deposition rate over that seen with CFD alone. In somecases, plasma or other activation is applied while one CFD reactant isflowing in order to produce parasitic CVD operations and thereby achievehigher deposition rates, a different class of films, etc.

In certain embodiments, two or more CFD phases may be employed and/ortwo or more CVD phases may be employed. For example, an initial portionof the film may be deposited by CFD, followed by an intermediate portionof the film being deposited by CVD, and a final portion of the filmdeposited by CFD. In such embodiments, it may be desirable to modify theCVD portion of the film, as by plasma treatment or etching, prior todepositing the later portion of the film by CFD.

A transition phase may be employed between the CFD and CVD phases. Theconditions employed during such transition phase different from thoseemployed in either the CFD or the CVD phases. Typically, though notnecessarily, the conditions permit simultaneous CFD surface reactionsand CVD type gas phase reaction. The transition phase typically involvesexposure to a plasma, which may be pulsed for example. Further, thetransition phase may involve delivery of one or more reactants a lowflow rate, i.e., a rate that is significantly lower than that employedin the corresponding CFD phase of the process.

Feature 6 (Deposit by CFD, Etch, and then Further Deposit by CFD)—Insuch embodiments, CFD deposition is performed for one or more cycles(typically a number of cycles) and then the resulting film is etched toremove, for example, some excess film at or near a recess entrance (acusp), followed by further cycles of CFD deposition. Other examples ofstructural features in the deposited film that may be etched in asimilar manner. The etchant chosen for this process will depend on thematerial to be etched. In some cases, the etch operation may beperformed with a fluorine containing etchant (e.g., NF3) or hydrogen.

In certain embodiments, a remote plasma is employed to produce theetchant. Generally, a remote plasma etches in a more isotropic fashionthan a direct plasma. A remote plasma generally provides a relativelyhigh fraction of radicals to the substrate. The reactivity of theseradicals may vary with the vertical position within the recess. At thetop of the feature, the radicals are more concentrated and consequentlywill etch at a higher rate, while further down the recess and at thebottom, some radicals will have been lost and therefore they will etchat a lower rate. This is of course a desirable reactivity profile foraddressing the problem of too much deposition occurring at the recessopening. An additional benefit of using a remote plasma in etching isthat the plasma is relatively gentle and hence unlikely to damage thesubstrate layer. This can be particularly beneficial when the underlyingsubstrate layer is sensitive oxidation or other damage.

Feature 7 (Tailoring the Film Composition with Additional Reactant)—Manyof the examples presented herein concern CFD processes employing one ortwo reactants. Further, many of the examples employ the same reactantsin every CFD cycle. However, this need not be the case. First, many CFDprocesses may employ three or more reactants. Examples include (i) CFDof tungsten using as reactants diborane, tungsten hexafluoride, andhydrogen, and (ii) CFD of silicon oxide using as reactants diborane,BTBAS, and oxygen. The diborane can be removed from the growing film orit can be incorporated into the film if appropriate.

Further, some examples may employ additional reactants in only some CFDcycles. In such examples, a basic CFD process cycle employs only thereactants to create the base film composition (e.g., silicon oxide orsilicon carbide). This basic process is performed in all or nearly allCFD cycles. However, some of the CFD cycles are executed as variantcycles and they deviate from the conditions of the normal depositioncycles. For example, they may employ one or more additional reactants.These variant cycles may also employ the same reactants employed in thebasic CFD process, although this need not be the case.

Such CFD processes are particularly beneficial in preparing doped oxidesor other doped materials as CFD films. In some implementations, dopantprecursors are included as the “additional” reactant in only a smallfraction of the CFD cycles. The frequency of adding the dopant isdictated by the desired concentration of dopant. For example, the dopantprecursor may be included in every 10th cycle of the base materialdeposition.

Unlike many other deposition processes, particularly those requiringthermal activation, the CFD process may be conducted at a relatively lowtemperature. Generally, the CFD temperature will be between about 20 and400 C. Such temperature may be chosen to permit deposition in thecontext of a temperature sensitive process such as deposition on aphotoresist core. In a specific embodiment, a temperature of betweenabout 20 and 100 C. is used for double patterning applications (using,e.g., photoresist cores). In another embodiment, a temperature ofbetween about 200 and 350 C. is employed for memory fabricationprocessing.

As suggested above, CFD is well suited for depositing films in advancedtechnology nodes. Thus, for example, CFD processing may be integrated inprocesses at the 32 nm node, the 22 nm node, the 16 nm node, the 11 nmnode, and beyond any of these. These nodes are described in theInternational Technology Roadmap for Semiconductors (ITRS), the industryconsensus on microelectronic technology requirements for many years.Generally they reference one-half pitch of a memory cell. In a specificexample, the CFD processing is applied to “2×” devices (having devicefeatures in the realm of 20-29 nm) and beyond.

While most examples of CFD films presented herein concern silicon basedmicroelectronic devices, the films may also find application in otherareas. Microelectronics or optoelectronics using non-siliconsemiconductors such as GaAs and other III-V semiconductors, as well asII-VI materials such as HgCdTe may profit from using the CFD processesdisclosed herein. Applications for conformal dielectric films in thesolar energy field, such as photovoltaic devices, in the electrochromicsfield, and other fields are possible.

FIG. 1 schematically shows a timing diagram 100 for an exampleembodiment of a plasma-activated CFD process. Two full CFD cycles aredepicted. As shown, each includes an exposure to reactant A phase 120,directly followed by an exposure to reactant B phase 140, a sweep ofreactant B phase 160, and finally a plasma activation phase 180. Plasmaenergy provided during plasma activation phases 180A and 180B activatesa reaction between surface adsorbed reactant species A and B. In thedepicted embodiments, no sweep phase is performed after one reactant(reactant A) is delivered. In fact, this reactant flows continuouslyduring the film deposition process. Thus, plasma is ignited whilereactant A is in the gas phase. Features 1-3 above are embodied in theexample of FIG. 1.

In the depicted embodiment, reactant gases A and B may co-exist in thegas phase without reacting. Accordingly, one or more of the processsteps described in the ALD process may be shortened or eliminated inthis example CFD process. For example, sweep steps after A ExposurePhases 120A and 120B may be eliminated.

The CFD process may be employed to deposit any of a number of differenttypes of film. While most of the examples presented herein, concerndielectric materials, the disclosed CFD processes may be employed toform films of conductive and semiconductor materials as well. Nitridesand oxides are featured dielectric materials, but carbides, oxynitrides,carbon-doped oxides, borides, etc. may also be formed. Oxides include awide range of materials including undoped silicate glass (USG), dopedsilicate glass. Examples of doped glasses included boron doped silicateglass (BSG), phosphorus doped silicate glass (PSG), and boron phosphorusdoped silicate glass (BPSG).

In some embodiments, a silicon nitride film may be formed by reaction ofa silicon-containing reactant and one or more of a nitrogen-containingreactant and/or a nitrogen-containing reactant blend. Examplesilicon-containing reactants include, but are not limited to,bis(tertiarybutylamino)silane (SiH₂(NHC(CH₃)₃)₂ or BTBAS),dichlorosilane (SiH₂Cl₂), and chlorosilane (SiH₃Cl). Examplenitrogen-containing reactants include, but are not limited to, ammonia,nitrogen, and tert-butyl amine ((CH₃)₃CNH₂ or t-butyl amine). An examplenitrogen-containing reactant blend, includes, but is not limited to, ablend of nitrogen and hydrogen.

Selection of one or more reactants may be driven by various film and/orhardware considerations. For example, in some embodiments, a siliconnitride film may be formed from reaction of dichlorosilane andplasma-activated nitrogen. Chemisorption of dichlorosilane to a siliconnitride surface may create a silicon-hydrogen terminated surface,liberating hydrogen chloride (HCl). An example of this chemisorptionreaction is schematically depicted in Reaction 1.

The cyclic intermediate shown in Reaction 1 may then be transformed intoa silicon amine terminated surface via reaction with plasma-activatednitrogen.

However, some molecules of dichlorosilane may chemisorb by alternativemechanisms. For example, surface morphology may hinder the formation ofthe cyclic intermediate depicted in Reaction 1. An example of anotherchemisorption mechanism is shown schematically in Reaction 2.

During subsequent plasma activation of nitrogen, the remaining chlorineatom of the intermediate species shown in Reaction 2 may be liberatedand may become activated by the plasma. This may cause etching of thesilicon nitride surface, potentially causing the silicon nitride film tobecome rough or hazy. Further, the residual chlorine atom may readsorb,physically and/or chemically, potentially contaminating the depositedfilm. This contamination may alter physical and/or electrical propertiesof the silicon nitride film. Further still, the activated chlorine atommay cause etch damage to portions of the process station hardware,potentially reducing the service life of portions of the processstation.

Thus, in some embodiments, chlorosilane may be substituted fordichlorosilane. This may reduce film contamination, film damage, and/orprocess station damage. An example of the chemisorption of chlorosilaneis schematically shown in Reaction 3.

While the example depicted in Reaction 3 uses chlorosilane as thesilicon-containing reactant, it will be appreciated that any suitablemono-substituted halosilane may be used.

As explained above, the depicted intermediate structures may react witha nitrogen source to form a silicon amine terminated surface of siliconnitride. For example, ammonia may be activated by a plasma, formingvarious ammonia radical species. The radical species react with theintermediate, forming the silicon amine terminated surface.

However, ammonia may physisorb strongly to surfaces of the reactantdelivery lines, process station, and exhaust plumbing, which may lead toextended purge and evacuation times. Further, ammonia may have a highreactivity with some gas phase silicon-containing reactants. For examplegas-phase mixtures of dichlorosilane (SiH₂Cl₂) and ammonia may createunstable species such as diaminosilane (SiH₂(NH₂)₂). Such species maydecompose in the gas phase, nucleating small particles. Small particlesmay also be formed if ammonia reacts with hydrogen chloride generatedduring chemisorption of a halosilane. Such particles may accumulate inthe process station where they may contaminate substrate surfaces,potentially leading to integrated device defects, and where they maycontaminate process station hardware, potentially leading to tool downtime and cleaning. The small particles may also accumulate in exhaustplumbing, may clog pumps and blowers, and may create a need for specialenvironmental exhaust scrubbers and/or cold traps.

Thus, in some embodiments, a substituted amine may be used as anitrogen-containing reactant. For example, various radicals formed fromplasma activation of an alkyl substituted amine, such as t-butyl amine,may be supplied to the process station. Substituted amines such ast-butyl amine may have a lower sticking coefficient on process hardwarethan ammonia, which may result in comparatively lower phyisorbptionrates and comparatively lower process purge time.

Further, such nitrogen-containing reactants may form halogenated saltsthat are comparatively more volatile than ammonium chloride. Forexample, t-butylammonium chloride may be more volatile than ammoniumchloride. This may reduce tool down time, device defect creation, andenvironmental abatement expense.

Further still, such nitrogen-containing reactants may form other amineprecursors via various byproduct reactions. For example, the reaction oft-butyl amine with dichlorosilane may form BTBAS. Thus, the sideproducts may provide alternate routes to form silicon nitride,potentially increasing film yield. In another example, substitutedamines may provide low temperature thermally activated routes to siliconnitride films. For example, t-butyl amine decomposes thermally attemperatures above 300° C. to form isobutylene and ammonia.

While the illustrative example provided above describes silicon nitridefilm formation using t-butyl amine, it will be appreciated that anysuitable substituted amine may be employed within the scope of thepresent disclosure. Suitable substituted amines may be selected, in someembodiments, based on thermodynamic characteristics and/or reactivitycharacteristics of the reactant. For example, the relative volatility ofhalogenated salts formed from the reactant may be considered, as may theexistence and selectivity of various thermal decomposition paths atrelevant temperatures.

Further, while the examples provided above describe the deposition ofsilicon nitride films, it will be appreciated that the principlesdiscussed above apply generally to the deposition of other films. Forexample, some embodiments may use suitable halosilanes in combinationwith a suitable oxygen-containing reactant species, such as an oxygenplasma, to deposit silicon oxides.

A non-limiting list of reactants, product films, and film and processproperty ranges are provided in Table 1.

TABLE 1 Temp. Press. Ref. Film Reactant A Reactant B Reactant C (C.)(torr) index SiO₂ BTBAS O₂ — 50-400 1-4 1.45-1.47 SiN SiH₃Cl O₂ — 50-4001-4 SiO₂ SiH(N(CH₃)₂)₃ O₂ — 50-400 1-4 1.45-1.47 SiN BTBAS NH₃ — 50-4001-4 1.80-2.05 SiN BTBAS — N₂/H₂ 50-400 1-4 1.80-2.05 SiN BTBAS NH₃ N₂/H₂50-400 1-4 1.80-2.05 SiN SiH₃Cl NH₃ Optionally 50-400 1-4 N₂/H₂ SiNSiH₃Cl t-butyl Optionally amine N₂/H₂ SiN SiH₂Cl₂ NH₃ Optionally 50-4001-4 1.80-2.05 N₂/H₂ SiN SiH₂Cl₂ t-butyl Optionally amine N₂/H₂ SiNSiH(CH₃)—(N(CH₃)₂)₂ NH₃ Optionally 50-400 1-4 1.80-2.05 N₂/H₂ SiNSiH(CH₃)(Cl₂) NH₃ Optionally 50-400 1-4 1.80-2.05 N₂/H₂ SiNSiHCl—(N(CH₃)₂)₂ NH₃ Optionally 50-400 1-4 1.80-2.05 N₂/H₂ SiN(Si(CH₃)₂NH)₃ NH₃ Optionally 50-400 1-4 1.80-2.05 N₂/H₂

FIG. 1 also shows an embodiment of a temporal progression of example CFDprocess phases for various CFD process parameters. FIG. 1 depicts twoexample deposition cycles 110A and 110B, though it will be appreciatedthat any suitable number of deposition cycles may be included in a CFDprocess to deposit a desired film thickness. Example CFD processparameters include, but are not limited to, flow rates for inert andreactant species, plasma power and frequency, substrate temperature, andprocess station pressure. Non-limiting parameter ranges for an examplesilicon dioxide deposition cycle using BTBAS and oxygen are provided inTable 2.

TABLE 2 Phase Reactant A Reactant B Plasma exposure exposure Sweepactivation phase phase phase phase Time (sec) continuing 0.25-10  0.25-10   0.25-10   BTBAS (sccm) n/a 0.5-5.0  0 0 O₂ (slm) 1-20 1-201-20 1-20 Ar (slm) 1-20 1-20 1-20 1-20 Pressure (torr) 1-4  1-4  1-4 1-4  Temp (C.) 50-400 50-400 50-400 50-400 HF Power (W) 0 0 0  50-2500LF Power (W) 0 0 0  0-2500

A CFD cycle typically contains an exposure phase for each reactant.During this “exposure phase,” a reactant is delivered to a processchamber to cause adsorption of the reactant on the substrate surface.Typically, at the beginning of an exposure phase, the substrate surfacedoes not have any appreciable amount of the reactant adsorbed. In FIG.1, at reactant A exposure phases 120A and B, reactant A is supplied at acontrolled flow rate to a process station to saturate exposed surfacesof a substrate. Reactant A may be any suitable deposition reactant;e.g., a principal reactant or an auxiliary reactant. In one examplewhere CFD produces a silicon dioxide film, reactant A may be oxygen. Inthe embodiment shown in FIG. 1, reactant A flows continuously throughoutdeposition cycles 110A and 110B. Unlike a typical ALD process, wherefilm precursor exposures are separated to prevent gas phase reaction,reactants A and B are allowed to mingle in the gas phase of someembodiments of a CFD process. As indicated above, in some embodimentsreactants A and B are chosen so that they can co-existence in the gasphase without appreciably reacting with one another under conditionsencountered in the reactor prior to application of plasma energy or theactivation of the surface reaction. In some cases, the reactants arechosen such that (1) a reaction between them is thermodynamicallyfavorable (i.e., Gibb's free energy <0) and (2) the reaction has asufficiently high activation energy that there is negligible reaction atthe desired deposition temperature. Various reactant combinationsmeeting these criteria are identified at other locations in thisdisclosure. Many such combinations include a primary reactant, whichcontributes an element that is solid at room temperature, and anauxiliary reactant, which does not. Examples of auxiliary reactants usedin some combinations include oxygen, nitrogen, alkyl amines, andhydrogen.

Continuously supplying reactant A to the process station may reduce oreliminate a reactant A flow rate turn-on and stabilization time comparedto an ALD process where reactant A is first turned on, then stabilizedand exposed to the substrate, then turned off, and finally removed froma reactor. While the embodiment shown in FIG. 1 depicts reactant Aexposure phases 120A and B as having a constant flow rate, it will beappreciated that any suitable flow of reactant A, including a variableflow, may be employed within the scope of the present disclosure.Further, while FIG. 1 shows reactant A having a constant flow rateduring the entire CFD cycle (deposition cycle 110A), this need not bethe case. For example, the flow rate of reactant A may decrease during Bexposure phases 140A and 140B. This may increase the partial pressure ofB and thereby increase the driving force of reactant B adsorbing on thesubstrate surface.

In some embodiments, reactant A exposure phase 120A may have a durationthat exceeds a substrate surface saturation time for reactant A. Forexample, the embodiment of FIG. 1 includes a reactant A post-saturationexposure time 130 in reactant A exposure phase 120A. Optionally,reactant A exposure phase 120A includes a controlled flow rate of aninert gas. Example inert gases include, but are not limited to,nitrogen, argon, and helium. The inert gas may be provided to assistwith pressure and/or temperature control of the process station,evaporation of a liquid precursor, more rapid delivery of the precursorand/or as a sweep gas for removing process gases from the processstation and/or process station plumbing.

At Reactant B exposure phase 140A of the embodiment shown in FIG. 1,reactant B is supplied at a controlled flow rate to the process stationto saturate the exposed substrate surface. In one example silicondioxide film, reactant B may be BTBAS. While the embodiment of FIG. 1depicts reactant B exposure phase 140A as having a constant flow rate,it will be appreciated that any suitable flow of reactant B, including avariable flow, may be employed within the scope of the presentdisclosure. Further, it will be appreciated that reactant B exposurephase 140A may have any suitable duration. In some embodiments, reactantB exposure phase 140A may have a duration exceeding a substrate surfacesaturation time for reactant B. For example, the embodiment shown inFIG. 1 depicts a reactant B post-saturation exposure time 150 includedin reactant B exposure phase 140A. Optionally, reactant B exposure phase140A may include a controlled flow of a suitable inert gas, which, asdescribed above, may assist with pressure and/or temperature control ofthe process station, evaporation of a liquid precursor, more rapiddelivery of the precursor and may prevent back-diffusion of processstation gases. In the embodiment shown in FIG. 11, an inert gas iscontinually supplied to the process station throughout reactant Bexposure phase 140A.

In some embodiments, plasma activation of deposition reactions mayresult in lower deposition temperatures than in thermally-activatedreactions, potentially reducing consumption of the available thermalbudget of an integrated process. For example, in some embodiments, aplasma activated CFD process may occur at room temperature.

While the CFD process embodiment depicted in FIG. 1 is plasma activated,it will be appreciated that other non-thermal energy sources may be usedwithin the scope of the present disclosure. Non-limiting examples ofnon-thermal energy sources include, but are not limited to, ultravioletlamps, downstream or remote plasma sources, inductively-coupled plasmas,and microwave surface wave plasmas.

Further, while many examples discussed herein include two reactants (Aand B), it will be appreciated that any suitable number of reactants maybe employed within the scope of the present disclosure. In someembodiments, a single reactant and an inert gas used to supply plasmaenergy for a surface decomposition reaction of the reactant may be used.Alternatively, as discussed above in the context of feature 7, someembodiments may use three or more reactants to deposit a film.

In some scenarios, surface adsorbed B species may exist as discontinuousislands on the substrate surface, making it difficult to achieve surfacesaturation of reactant B. Various surface conditions may delaynucleation and saturation of reactant B on the substrate surface. Forexample, ligands released on adsorption of reactants A and/or B mayblock some surface active sites, preventing further adsorption ofreactant B. Accordingly, in some embodiments, continuous adlayers ofreactant B may be provided by modulating a flow of and/or discretelypulsing reactant B into the process station during reactant B exposurephase 140A. This may provide extra time for surface adsorption anddesorption processes while conserving reactant B compared to a constantflow scenario.

Additionally or alternatively, in some embodiments, one or more sweepphases may be included between consecutive exposures of reactant B. Forexample, the embodiment of FIG. 2 schematically shows an example CFDprocess timing diagram 200 for a deposition cycle 210. At reactant Bexposure phase 240A, reactant B is exposed to the substrate surface.Subsequently, at sweep phase 260A, reactant B is turned off, and gasphase species of reactant B are removed from the process station. In onescenario, gas phase reactant B may be displaced by a continuous flow ofreactant A and/or the inert gas. In another scenario, gas phase reactantB may be removed by evacuating the process station. Removal of gas phasereactant B may shift an adsorption/desorption process equilibrium,desorbing ligands, promoting surface rearrangement of adsorbed B tomerge discontinuous islands of adsorbed B. At reactant B exposure phase240B, reactant B is again exposed to the substrate surface. While theembodiment shown in FIG. 2 include one instance of a reactant B sweepand exposure cycle, it will be appreciated that any suitable number ofiterations of alternating sweep and exposure cycles may be employedwithin the scope of the present disclosure.

Returning to the embodiment of FIG. 1, prior to activation by the plasmaat 180A, gas phase reactant B may be removed from the process station insweep phase 160A in some embodiments. A CFD cycle may include one ormore sweep phases in addition to the above-described exposure phases.Sweeping the process station may avoid gas phase reactions wherereactant B is susceptible to plasma activation. Further, sweeping theprocess station may remove surface adsorbed ligands that may otherwiseremain and contaminate the film. Examples sweep gases include, but arenot limited to, argon, helium, and nitrogen. In the embodiment shown inFIG. 1, sweep gas for sweep phase 160A is supplied by the inert gasstream. In some embodiments, sweep phase 160A may include one or moreevacuation subphases for evacuating the process station. Alternatively,it will be appreciated that sweep phase 160A may be omitted in someembodiments.

Sweep phase 160A may have any suitable duration. In some embodiments,increasing a flow rate of a one or more sweep gases may decrease theduration of sweep phase 160A. For example, a sweep gas flow rate may beadjusted according to various reactant thermodynamic characteristicsand/or geometric characteristics of the process station and/or processstation plumbing for modifying the duration of sweep phase 160A. In onenon-limiting example, the duration of a sweep phase may be optimized byadjustment of the sweep gas flow rate. This may reduce deposition cycletime, which may improve substrate throughput.

A CFD cycle, typically includes an “activation phase” in addition to theexposure and optional sweep phases described above. The activation phaseserves to drive the reaction of the one or more reactants adsorbed onthe substrate surface. At plasma activation phase 180A of the embodimentshown in FIG. 1, plasma energy is provided to activate surface reactionsbetween surface adsorbed reactants A and B. For example, the plasma maydirectly or indirectly activate gas phase molecules of reactant A toform reactant A radicals. These radicals may then interact with surfaceadsorbed reactant B, resulting in film-forming surface reactions. Plasmaactivation phase 180A concludes deposition cycle 110A, which in theembodiment of FIG. 1 is followed by deposition cycle 110B, commencingwith reactant A exposure phase 120B.

In some embodiments, the plasma ignited in plasma activation phase 180Amay be formed directly above the substrate surface. This may provide agreater plasma density and enhanced surface reaction rate betweenreactants A and B. For example, plasmas for CFD processes may begenerated by applying a radio frequency (RF) field to a low-pressure gasusing two capacitively coupled plates. In alternative embodiments, aremotely generated plasma may be generated outside of the main reactionchamber.

Any suitable gas may be used to form the plasma. In a first example, andinert gas such as argon or helium may be used to form the plasma. In asecond example, a reactant gas such as oxygen or ammonia may be used toform the plasma. In a third example, a sweep gas such as nitrogen may beused to form the plasma. Of course, combinations of these categories ofgases may be employed. Ionization of the gas between the plates by theRF field ignites the plasma, creating free electrons in the plasmadischarge region. These electrons are accelerated by the RF field andmay collide with gas phase reactant molecules. Collision of theseelectrons with reactant molecules may form radical species thatparticipate in the deposition process. It will be appreciated that theRF field may be coupled via any suitable electrodes. Non-limitingexamples of electrodes include process gas distribution showerheads andsubstrate support pedestals. It will be appreciated that plasmas for CFDprocesses may be formed by one or more suitable methods other thancapacitive coupling of an RF field to a gas.

Plasma activation phase 180A may have any suitable duration. In someembodiments, plasma activation phase 180A may have a duration thatexceeds a time for plasma-activated radicals to interact with allexposed substrate surfaces and adsorbates, forming a continuous filmatop the substrate surface. For example, the embodiment shown in FIG. 1includes a plasma post-saturation exposure time 190 in plasma activationphase 180A.

As explained more fully below, and as suggested in the discussion offeature 4 above, extending a plasma exposure time and/or providing aplurality of plasma exposure phases may provide a post-reactiontreatment of bulk and/or near-surface portions of the deposited film. Inone scenario, decreasing surface contamination by plasma treatment mayprepare the surface for adsorption of reactant A. For example, a siliconnitride film formed from reaction of a silicon-containing reactant and anitrogen-containing reactant may have a surface that resists adsorptionof subsequent reactants. Treating the silicon nitride surface with aplasma may create hydrogen bonds for facilitating subsequent adsorptionand reaction events.

In some embodiments, film properties, such as film stress, dielectricconstant, refractive index, etch rate may be adjusted by varying plasmaparameters, which will be discussed in more detail below. Table 3provides an example list of various film properties for three exampleCFD silicon dioxide films deposited at 400 degrees Celsius. Forreference purposes, Table 3 also includes film information for anexample PECVD silicon dioxide film deposited at 400 degrees Celsius.

TABLE 3 NU Film SiO₂ Dep. rate ((max − min)/ NU Ref. stress DielectricWet etch Process (ang./cycle) average) (1 □) Index (MPa) constant rateratio 1 sec. 0.9 5% 2% 1.456 −165 6.6 7.87 200 W O₂ plasma (HF only) 10sec. 0.6 5% 2% 1.466 −138 3.9 1.59 1000 W O₂ plasma (HF only) 10 sec.0.6 12%  5% 1.472 −264 3.9 1.55 1000 W O₂ plasma (HF/LF) PECVD SiO₂ 6003% 1% 1.477 −238 4.2 5.28

For example, FIG. 3 schematically shows an embodiment of a CFD processtiming diagram 300 including a deposition phase 310 followed by a plasmatreatment phase 390. It will be appreciated that any suitable plasma maybe used during a plasma treatment phase. In a first scenario, a firstplasma gas may be used during activation in the deposition cycle and asecond, different plasma gas may be used during a plasma treatmentphase. In a second scenario, a second, different plasma gas maysupplement a first plasma gas during the plasma treatment phase.Non-limiting parameter ranges for an example in-situ plasma treatmentcycle are provided in Table 4.

TABLE 4 Phase Plasma treatment Plasma treatment sweep phase activationphase Time (sec) 0.25-10.0  0.25-10.0  Ar (sccm) 1-20 1-20 Pressure(torr) 1-4  1-4  Temp (C.) 50-400 50-400 HF Power (W)  50-2500  50-2500LF Power (W)  0-2500  0-2500

At plasma activation phase 380 shown in FIG. 3, the substrate surface isexposed to a plasma to activate a film deposition reaction. As depictedin the embodiment shown in FIG. 3, the process station is provided witha continuous flow of reactant A, which may be, e.g., an auxiliaryreactant such as oxygen, and an inert gas at plasma treatment sweepphase 390A. Sweeping the process station may remove volatilecontaminants from the process station. While a sweep gas is shown inFIG. 3, it will be appreciated that any suitable reactant removal methodmay be used within the scope of the present disclosure. At plasmatreatment activation phase 390B, a plasma is ignited to treat the bulkand/or near-surface region of the newly deposited film.

While the embodiment of FIG. 3 includes one instance of a CFD cycleincluding a plasma treatment phase, it will be appreciated that anysuitable number of iterations may be employed within the scope of thepresent disclosure. Further, it will be appreciated that one or moreplasma treatment cycles may be inserted at intervals (regular orotherwise) between normal deposition cycles. For example, FIG. 4 showsan embodiment of a CFD process timing diagram 400 including a plasmatreatment phase inserted between two deposition cycles. While theembodiment of FIG. 4 includes a plasma treatment cycle inserted betweentwo deposition cycles, it will be appreciated that any suitable numberof deposition cycles may precede or follow one or more plasma treatmentcycles. For example, in a scenario where a plasma treatment is used toalter a film density, a plasma treatment cycle may be inserted afterevery tenth deposition cycle. In a scenario where a plasma treatment isused to prepare a surface for adsorption and reaction events, a plasmatreatment phase may be incorporated in every CFD cycle, e.g., after eachCFD deposition phase.

Plasma treatment of the deposited film may alter one or more physicalcharacteristics of the film. In one scenario, a plasma treatment maydensify a newly deposited film. Densified films may be moreetch-resistant than non-densified films. For example, FIG. 5 shows anembodiment of a comparison 500 of etch rates for example CFD processedsilicon dioxide films relative to thermally grown silicon dioxide films.The example film embodiments of FIG. 5 were deposited over a range oftemperatures from 50 to 400 degrees Celsius by CFD processes 502 and504. For reference, relative etch rates for undoped silicate glass (USG)and silicon dioxide spacer layers deposited by plasma-enhanced CVDprocesses are displayed in FIG. 5. Films produced by process 502, whichincluded a one-second high-frequency oxygen plasma activation phase ineach deposition cycle, were approximately one-half as resistant to adilute hydrofluoric acid wet etch (100:1 H2O:HF) as film 504, whichincluded a ten-second high-frequency oxygen plasma activation phase ineach deposition cycle. Accordingly, it will be appreciated that varyingone or more aspects of the plasma activation phase and/or including oneor more plasma treatment cycles may vary an etch rate of a depositedfilm.

In another scenario, plasma treatment of a film may vary the stresscharacteristics of the film. For example, FIG. 6 shows an embodiment ofa correlation 600 between wet etch rate ratio and film stress forexample CFD silicon dioxide films. In the embodiment shown in FIG. 6,decreases in the wet etch rate ratio by, for example, extending a plasmaexposure time, may increase a compressive film stress.

In another scenario, plasma treatment of a deposited film may providetransient differential removal of trace film contaminants (e.g.,hydrogen, nitrogen and/or carbon in an example silicon dioxide film)relative to other film constituents (e.g., silicon and/or oxygen in anexample silicon dioxide film). For example, FIG. 7 shows an embodimentof a correlation 700 between deposition temperature, plasma exposuretime, and film contaminant concentrations. In the embodiment shown inFIG. 7, a CFD silicon dioxide film 704 deposited at 50 degrees Celsiusand having a ten-second oxygen plasma activation phase exhibits lowerconcentrations of hydrogen and carbon than a CFD silicon dioxide film702 deposited at the same temperature but having a one-second oxygenplasma activation phase. Modifying contaminant concentrations in a filmmay modify electrical and/or physical properties of the film. Forexample, modulating carbon and/or hydrogen content may modulate a filmdielectric constant and/or a film etch rate. Accordingly, it will beappreciated that varying one or more aspects of the plasma activationphase and/or including one or more plasma treatment cycles may providean approach for varying film composition.

While the plasma treatment discussed above relates to an oxygen plasmatreatment, it will be appreciated that any suitable plasma treatment maybe employed without departing from the scope of the present embodiment.For example, in some embodiments a substituted amine may be employed asa nitrogen-containing reactant in a suitable CFD process in place ofNH₃. Although replacement of NH₃ with a substituted amine (e.g., analkyl amine like t-butyl amine) for conformal SiN deposition may providea number of benefits, in some instances, the deposited film may includecarbon residue originating from the alkyl amine reactant (e.g., carbonresidue from the three methyl groups included each t-butyl aminemolecule (NH₂—(CH₃)₃)). This in-film carbon may result in electricalleakage and may render the film unusable for some dielectric barrierapplications.

Thus, in some embodiments, igniting a hydrogen plasma during SiN filmdeposition may reduce carbon residue in the SiN film, which maycomparatively improve the insulating character of the film. In someexamples, the reduction in carbon residue may be readily observable inFTIR spectra. For example, the SiN:C—H levels may be reduced fromapproximately 10% atomic to approximately 1% atomic.

Therefore, in some embodiments, a silicon nitride film may be depositedwith a CFD process using an alkyl amine or a mixture of alkyl aminesincluded in the nitrogen-containing reactant and one or more instancesof a hydrogen plasma treatment. It will be appreciated that any suitablehydrogen plasma may be employed without departing from the scope of thepresent disclosure. Thus, in some embodiments, an admixture of H₂ with agas such as He or Ar, or other H-containing gases, or active H atomsproduced by a remote plasma source, may be used to treat the depositedfilm. Further, in some embodiments, the carbon content of the film maybe tuned to any suitable concentration by varying one or more of thenumber of treatment pulses and their duration, the intensity of thetreatment plasma, the substrate temperature, and the treatment gascomposition.

While the hydrogen plasma treatment discussed above relates to a siliconnitride film, it will be appreciated that application of a suitablehydrogen plasma treatment may be used to adjust the carbon content ofother CFD deposited films, including, but not limited to, SiOx, GeOx,and SiOxNy.

Certain embodiments disclosed herein pertain to ultraviolet treatment(with or without plasma treatment) of oxide CFD films. The treatment maymitigate defects in the oxide and improve electrical properties such asCV characteristics of a gate dielectric. Device and package applicationsemploying CFD oxides that can benefit from such treatment includethru-silicon vias, logic technology employing gate oxides, shallowtrench isolation (STI), thin thermal oxidation formed afterSTI-photoresist strip, sacrificial oxide (e.g., ˜60 A) before a P-wellimplant, post “well” thermal oxide growth, gate/channel oxide, DRAM PMDPECVD Oxide.

In some cases, untreated CFD oxide films have been observed to haverelatively poor electrical performance due to, it is believed, fixedcharge in the as deposited film. For example, some films have been foundto have significant within-wafer Vfb variations. Such problems have beenresolved by using a post-deposition treatment with UV-radiation and/or athermal anneal in the presence of hydrogen. It is believed that thisprocess passivates and/or alleviates defects related to fixed charge atthe (1) oxide to silicon interface or (2) within the depositeddielectric film or (3) at the air to oxide surface (surface charge).Using such treatment, the Vfb spread for as deposited oxide has beentightened from 8.3V to about 1.5V after UV cure.

While the these embodiments are primarily concerned with improving oxidefilms, the disclosed method may be applied generally to the growth ofdielectrics, metals, metal to dielectric interface engineering. Specificdielectric materials include, for example, silicon oxides, includingdoped silicon oxides, silicon carbides, silicon oxycarbides, siliconnitrides, silicon oxynitrides, and ashable hard mask materials.

Examples of treatments that may be applied to improve dielectricproperties include the following:

(A) Post deposition treatment of dielectric films synthesized by CFDwith UV cure and then hydrogen-anneal. In the simplest embodiment, UVtreatment may be used alone to reduce fixed charge.

(B) Pre-treatment of the substrate prior to CFD-dielectric filmdeposition with treatments including: H₂-plasma, N₂-plasma,N₂/H₂-plasma, NH₃-plasma, Ar-plasma, He-plasma, He anneal, H₂-anneal,NH₃-anneal, and UV cure in the presence of He, H₂, Ar, N₂, H₂/N₂-forminggas, NH₃. Plasma processing may be enabled with various plasmagenerators including, though not limited to, microwave, ICP-remote,direct and the like.

(C) Concurrent treatment (curing during deposition) with treatmentsincluding: H₂-plasma, N₂-plasma, N₂/H₂-plasma, NH₃-plasma, Ar-plasma,He-plasma, He anneal, H₂-anneal, NH₃-anneal, and UV cure in the presenceof He, H₂, Ar, N₂, H₂/N₂-forming gas, NH₃. Plasma processing may beimplemented with various plasma generators including, though not limitedto, microwave, ICP-remote, direct and others known to those in the art.Isotropic and directional processing may be applied including, thoughnot limited to, remote plasma, UV exposure, direct plasma, and microwaveplasma. An example method includes intermittent treatment of the filmbetween groups of CFD cycles. A group of CFD cycles may vary from about1 to 10000 cycles. A typical scenario includes: (1) 5 cycles of CFDoxide growth followed by (2) one or more film treatments with any of themethods described above (e.g., He-plasma, UV-treatment), followed by (3)5 cycles of CFD oxide growth. This method may be used to grow a film ofany desired thickness.

(D) UV treatment imparted as byproduct by any plasma listed above (e.g.,a helium plasma emits UV radiation).

One example of a procedure for in situ “cure” during the CFD cyclinginvolves the following operations:

-   -   UV treatment via He-plasma    -   BTBAS dose    -   Purge    -   O2/Ar-RF plasma activation    -   Purge    -   Repeat steps 1-5 to yield a film of desired thickness.

A range of UV cure conditions may be employed in any of the listedcontexts. Generally, the pedestal temperature will be maintained betweenabout 250 and 500 C. during the cure. For many device fabricationapplications, the upper temperature will be limited to 450 C. or even400 C. The ambient employed during the cure may be inert or reactive.Examples of gases that may be present during the cure include helium,argon, nitrogen, forming gas, and ammonia. The flow rate of such gasesmay be about 2 to 20,000 sccm, preferably about 4000 to 18,000 sccm. Thepower of the UV lamp may, for example, about 2-10 kW, and preferablybetween about 3.5 and 7 kW. An appropriate duration of exposure to UVfrom such source is between about 20 and 200 seconds (e.g., about 90seconds). Finally, the pressure may be held at a level between 0 Torrand about 40 Torr.

In a specific embodiment, an effective treatment of CFD oxide wasobtained using the following conditions:

-   -   Pedestal temperature=400 C.    -   Ambient=He    -   Pressure=40 Torr He    -   Flow rate=10,000 sccm

In some embodiments, a thermal anneal of the oxide is performed afterthe UV cure operation. In one example, the following conditions wereused in the anneal:

-   -   Ped T=400 C.    -   Ambient=H2+N2    -   Pressure=2.5 Torr    -   Flow rates=750 sccm H2; 3000 sccm N2

The physical and electrical characteristics of the deposited film mayalso be altered by adjusting other process parameters, such asdeposition temperature. For example, correlation 700 of the embodimentdepicted in FIG. 7 also shows an example relationship between CFD filmdeposition temperature and film contaminants concentration. As filmdeposition temperature increases, incorporation of film contaminantsdecreases. In another example, the embodiment shown in FIG. 5illustrates that a wet etch rate ratio of example silicon dioxide CFDfilms decreases as deposition temperature increases, as described above.Other deposition parameters that may be adjusted to tune the filmproperties include RF power, RF frequency, pressure, and flow rates.Further, in some embodiments, film characteristics may be altered byaltering a reactant selection. For example, a hydrogen content of asilicon dioxide film may be reduced by using tetra isocyanate silane(TICS) as a silicon-containing reactant and oxygen and/or nitrous oxideas an oxygen-containing reactant.

It will be appreciated that variation of physical and/or electrical filmcharacteristics, like those discussed above, may provide opportunitiesto adjust device performance and yield, as well as opportunities tomodify aspects of device manufacturing process integration. As onenon-limiting example, the ability to tune etch rate characteristics of aCFD silicon dioxide film may make the film a candidate for etch stop,hard mask, and other process integration applications. Accordingly,various embodiments of CFD-produced films are provided herein forapplication throughout an integrated semiconductor device fabricationprocess.

In one scenario, a CFD process may deposit a conformal silicon dioxidefilm on a non-planar substrate. For example, a CFD silicon dioxide filmmay be used for gap fill of structures, such as a trench fill of shallowtrench isolation (STI) structures. While the various embodimentsdescribed below relate to a gap fill application, it will be appreciatedthat this is merely a non-limiting, illustrative application, and thatother suitable applications, utilizing other suitable film materials,may be within the scope of the present disclosure. Other applicationsfor CFD silicon dioxide films include, but are not limited to,interlayer dielectric (ILD) applications, intermetal dielectric (IMD)applications, pre-metal dielectric (PMD) applications, dielectric linersfor through-silicon via (TSV) applications, resistive RAM (ReRAM)applications, and/or stacked capacitor fabrication in DRAM applications.

Doped silicon oxide may be used as a diffusion source for boron,phosphorus, or even arsenic dopants. For example, a boron doped silicateglass (BSG), a phosphorus doped silicate glass (PSG), or even a boronphosphorus doped silicate glass (BPSG) could be used. Doped CFD layerscan be employed to provide conformal doping in, for example,three-dimensional transistor structures such as multi-gate FinFET's andthree-dimensional memory devices. Conventional ion implanters cannoteasily dope sidewalls, especially in high aspect ratio structures. CFDdoped oxides as diffusion sources have various advantages. First, theyprovide high conformality at low temperature. In comparison,low-pressure CVD produced doped TEOS (tetraethylorthosilicate) is knownbut requires deposition at high temperature, and sub-atmospheric CVD andPECVD doped oxide films are possible at lower temperature but haveinadequate conformality. Conformality of doping is important, but so isconformality of the film itself, since the film typically is asacrificial application and will then need to be removed. Anon-conformal film typically faces more challenges in removal, i.e. someareas can be overetched. Additionally, CFD provides extremely wellcontrolled doping concentration. As mentioned, a CFD process can providefrom a few layers of undoped oxide followed by a single layer of doping.The level of doping can be tightly controlled by the frequency withwhich the doped layer is deposited and the conditions of the dopingcycle. In certain embodiments, the doping cycle is controlled by forinstance using a dopant source with significant steric hindrance. Inaddition to conventional silicon-based microelectronics, otherapplications of CFD doping include microelectronics and optoelectronicsbased on III-V semiconductors such as GaAs and II-VI semiconductors suchas HgCdTe, photovoltaics, flat panel displays, and electrochromictechnology.

Some gap fill processes involve two film deposition steps performed ondifferent deposition tools, requiring a vacuum break and air exposurebetween deposition processes. FIG. 8 schematically shows an examplenon-planar substrate 800 including a plurality of gaps 802. As depictedin FIG. 8, gaps 802 may have varying aspect ratios, which may be definedas a ratio of gap depth (H) to gap width (W) for each gap 802. Forexample, a logic area of an integrated semiconductor device may havevarying gap aspect ratios corresponding to different logic devicestructures.

As depicted in FIG. 8, non-planar substrate 800 is covered by a thin,conformal film 804. While conformal film 804 has completely filled gap802A, gaps 802B and 802C remain open. Closing gaps 802B and 802C with aconformal film may lead to extended process times. Thus, in someapproaches, a thicker film may be deposited ex-situ by a higherdeposition rate process, such as a CVD and/or PECVD method. However,ex-situ deposition of gap fill films may reduce wafer throughput in aproduction line. For example, substrate handling and transfer timebetween a deposition tools may reduce a number of substrate processingactivities during a production period. This may diminish production linethroughput and may require the installation and maintenance ofadditional process tools in the production line.

Further, while gap 802C may have an aspect ratio suitable for agas-phase deposition process, 802B may have an aspect ratio that maylead to incomplete filling by a higher deposition rate process and mayform a keyhole void. For example, FIG. 10 shows an example high aspectratio structure 1000 formed in substrate 1002. As depicted in FIG. 10,bread loafing effects during the deposition of thicker film 1006 haveproduced keyhole void 1008. Keyhole voids may be re-opened and filledwith conductive films in subsequent processes, which may lead to deviceshorting.

Some approaches to addressing high aspect ratio gaps such as gap 802Binclude providing device design rules that avoid creation of such gaps.However, such design rules may require additional masking steps, maymake device design difficult, and/or may lead to increased integratedsemiconductor device area, which may increase manufacturing cost. Thus,in some embodiments, a CFD process may include an in-situ transitionfrom a CFD process to a CVD and/or a PECVD process. For example, FIG. 9shows an embodiment of a CFD process timing diagram 900 that has beendivided into three phases. CFD process phase 902 depicts an example CFDprocess cycle. For clarity, a single CFD process cycle is shown in theembodiment depicted in FIG. 9, though it will be appreciated that anysuitable number of CFD process cycles and plasma treatment cycles may beincluded in CFD process phase 902. A transition phase 904 follows CFDprocess phase 902. As depicted in the embodiment of FIG. 9, transitionphase 904 includes aspects of both a CFD process and a PECVD process.Specifically, reactant B is provided to the process station past the endof reactant B exposure phase 904A so that reactants A and B are bothpresent in the gas phase during plasma activation phase 904B. This mayprovide PECVD-type gas phase reactions concurrently with CFD-typesurface reactions. While transition phase 904 includes only oneiteration of reactant B exposure phase 904A and plasma activation phase904B, it will be appreciated that any suitable number of iterations maybe included within a transition phase.

In some embodiments, a plasma generator may be controlled to provideintermittent pulses of plasma energy during plasma activation phase904B. For example, the plasma may be pulsed at one or more frequenciesincluding, but not limited to, frequencies between of 10 Hz and 150 Hz.This may enhance step coverage by reducing a directionality of ionbombardment in comparison to a continuous plasma. Further, this mayreduce ion bombardment damage to the substrate. For example, photoresistsubstrates may be eroded by ion bombardment during a continuous plasma.Pulsing the plasma energy may reduce photoresist erosion.

In the embodiment shown in FIG. 9, the flow rate of reactant B duringplasma activation phase 904B is less than the flow rate of reactant Bduring reactant B exposure phase 904A. Thus, reactant B may be“trickled” into the process station during plasma activation phase 904B.This may provide a gas-phase PECVD reaction supplementing the CFD-typesurface reactions. However, it will be appreciated that, in someembodiments, flow rate of reactant B may be varied during a singleplasma activation phase or over the course of a transition phase. Forexample, in a transition phase including two iterations of reactant Bexposure and plasma activation, a flow rate of reactant B during a firstplasma activation phase may be lower than a flow rate of reactant Bduring the second plasma activation phase. Varying a flow rate ofreactant B during plasma activation phase 904B may provide a smoothtransition from the step-coverage characteristics of CFD process phase902 to the deposition rate characteristics of PECVD process phase 906.

In some embodiments, a CFD process may include an in-situ etch forselectively removing a re-entrant portion of deposited film.Non-limiting parameter ranges for an example silicon dioxide depositionprocess including an in-situ etch for a gap fill CFD process areprovided in Table 5.

TABLE 5 Phase Reactant Reactant A B Plasma exposure exposure Sweepactivation Etch phase phase phase phase phase Time continuing 0.25-10.00.25-10.0  0.25-10.0  0.25-10.0  (sec) BTBAS — 0.5-2.0 0 0 0 (sccm) O₂1-20  1-20 1-20 1-20 0 (slm) NF₃ 0 0 0 0 1-15 (sccm) Ar 1-20  1-20 1-201-20 1-20 (slm) Pressure 1-4  1-4 1-4  1-4  1-4  (torr) Temp 50-400 50-400 50-400 50-400 50-400 (C.) HF 0 0 0  50-2500  50-2500 Power (W)LF 0 0 0  0-2500  0-2500 Power (W)

FIG. 11 shows an embodiment of a CFD process timing diagram 1100including a deposition phase 1102, an etch phase 1104, and a subsequentdeposition phase 1106. At deposition phase 1102 of the embodiment shownin FIG. 11, film is deposited onto the exposed surfaces of thesubstrate. For example, deposition phase 1102 may include one or moreCFD process deposition cycles.

At etch phase 1104 of the embodiment of FIG. 11, reactants A and B areturned off and an etch gas is introduced to the process station. Onenon-limiting example of an etch gas is nitrogen trifluoride (NF3). Inthe embodiment depicted in FIG. 11, the etch gas is activated by aplasma ignited during etch phase 1104. Various process parameters, suchas process station pressure, substrate temperature, etch gas flow rate,may be adjusted during etch phase 1104 for selectively removing are-entrant portion of a deposited film on a non-planar substrate. Anysuitable etch process may be employed within the scope of the presentdisclosure. Other example etch processes include, but are not limitedto, reactive ion etching, non-plasma vapor phase etching, solid phasesublimation, and adsorption and directional activation (e.g., by ionbombardment) of the etch species.

In some embodiments, incompatible gas phase species may be removed fromthe process station before and after etching the film. For example, theembodiment of FIG. 11 includes a continuous flow of an inert gas afterreactants A and B have been turned off and after the etch gas has beenturned off during etch phase 1104.

At the conclusion of etch phase 1104, a deposition phase 1106 begins,further filling gaps on the non-planar substrate. Deposition phase 1106may be any suitable deposition process. For example, deposition phase1106 may include one or more of a CFD process, a CVD process, a PECVDprocess, etc. While the embodiment of FIG. 11 shows a single etch phase1104, it will be appreciated that a plurality of in-situ etch processesmay be inserted at intervals among multiple deposition phases of anysuitable type during a gap fill process.

FIGS. 12A-12C depict example cross-sections of a non-planar substrate atvarious phases of an embodiment of the in-situ deposition and etchprocesses described above. FIG. 12A shows a cross-section of an examplenon-planar substrate 1200, including a gap 1202. Gap 1202 is coveredwith a thin film 1204. Thin film 1204 is nearly conformal with gap 1202,but thin film 1204 includes a re-entrant portion 1206 near the top ofgap 1202.

In the embodiment depicted in FIG. 12B, re-entrant portion 1206 of thinfilm 1204 has been selectively removed and that an upper region 1204A ofthin film 1204 is thinner than a lower region 1204B. Selective removalof the re-entrant portion and/or sidewall angle adjustment may beachieved by imposing mass transfer limitations and/or lifetimelimitations on the active etch species. In some embodiments, selectiveetching at the top of gap 1202 may also adjust a sidewall angle of gap1202, so that gap 1202 is wider at the top than at the bottom. This mayfurther reduce bread loafing effects in subsequent deposition phases. Inthe embodiment shown in FIG. 12C, after a subsequent deposition phase,gap 1202 is nearly filled and exhibits no voids.

Another embodiment of an in-situ etch process is shown in FIG. 15, whichdepicts a through-silicon via (TSV) 2500 for a copper electrode. Someexample TSVs have depths of approximately 105 microns and diameters ofapproximately 6 microns, giving an approximately 17.5:1 aspect ratio,and may have a thermal budget ceiling of approximately 200 degreesCelsius. As shown in the embodiment of FIG. 15, through-silicon via 2500is covered by a dielectric isolation layer 2502 to electrically isolatea silicon substrate from a metal-filled via. Example dielectricisolation layer materials include, but are not limited to, siliconoxide, silicon nitride, a low-k dielectric material. In someembodiments, the example etch processes described above may besupplemented with physical sputtering of the re-entrant portion using asuitable sputter gas, such as argon.

Other example applications for CFD films include, but are not limited toconformal low-k films (e.g., k approximately 3.0 or lower in somenon-limiting examples) for back-end-of-line interconnect isolationapplications, conformal silicon nitride films for etch stop and spacerlayer applications, conformal antireflective layers, and copper adhesionand barrier layers. Many different compositions of low-k dielectrics forBEOL processing can be fabricated using CFD. Examples include siliconoxides, oxygen doped carbides, carbon doped oxides, oxynitrides, and thelike.

In another example, in one integrated process scenario, a silicondioxide spacer layer may be deposited over a photoresist “core.” Use ofa photoresist core instead of an alternative core material (such as asilicon carbide layer) may eliminate a patterning step in the integratedprocess. The process may involve patterning photoresist using normallithographic techniques and then depositing a thin layer of CFD oxidedirectly over that core. A directional dry etch process may be then usedto remove the CFD oxide film at the top of the patterned photoresist andat the bottom leaving only material along the sidewall of the patternedphotoresist (consider trenches). At this stage, simple ashing can beused to remove the exposed core leaving behind the CFD oxide. Where oncethere was a single photoresist line, now there are two CFD-oxide lines.In this manner the process doubles the pattern density; hence it issometimes referred to as “double patterning”. Unfortunately, use of aphotoresist core may limit a spacer layer deposition temperature to lessthan 70 degrees Celsius, which may be less than deposition temperaturesfor conventional CVD, PECVD, and/or ALD processes. Thus, in someembodiments, a low temperature CFD silicon dioxide film may be depositedat temperatures below 70 degrees Celsius. It will be appreciated thatother potential integrated process applications exist for suitableCFD-generated films within the scope of the present disclosure.Additionally, in various embodiments, a nitride such as a siliconnitride deposited as above may be employed as a conformal diffusionbarrier layer and/or etch stop in various stages of semiconductor devicemanufacture.

While the various CFD deposition processes described above have beendirected at depositing, treating, and/or etching single film types, itwill be appreciated that some CFD processes within the scope of thepresent disclosure may include in-situ deposition of a plurality of filmtypes. For example, alternating layers of film types may be depositedin-situ. In a first scenario, a double spacer for a gate device may befabricated by in-situ deposition of a silicon nitride/silicon oxidespacer stack. This may reduce cycle time and increase process stationthroughput, and may avoid interlayer defects formed by potential filmlayer incompatibility. In a second scenario, an antireflective layer forlithographic patterning applications may be deposited as a stack of SiONor amorphous silicon and SiOC with tunable optical properties.

In certain embodiments, a dopant containing source layer is formed by aconformal film deposition process. The layer is termed a “source” layerbecause it provides a source of dopant species (e.g., dopant atoms suchas boron, phosphorus, gallium, and/or arsenic). The doped CFD layerserves as a source of dopant for doping an underlying (or overlying)structure in a device. After the source layer is formed (or during itsformation), the dopant species are driven or otherwise incorporated intoadjacent structures in the device being fabricated. In certainembodiments, the dopant species are driven by an annealing operationduring or after forming the conformal dopant source film. The highlyconformal nature of CFD permits doping non-conventional devicestructures, including structures which require doping in threedimensions. The CFD dopant source layer is typically formed by one ormore of the processes described herein, but includes the additionalprocess operation of incorporating a dopant species. In someembodiments, a dielectric layer serves as the base source layer intowhich the dopant species is incorporated.

For example, doped silicon oxide may be used as a diffusion source forboron, phosphorus, arsenic, etc. For example, a boron doped silicateglass (BSG), a phosphorus doped silicate glass (PSG), or a boronphosphorus doped silicate glass (BPSG) can be used.

Doped CFD layers can be employed to provide conformal doping in, forexample, three-dimensional transistor structures such as multi-gateFinFETs and three-dimensional memory devices. Examples of somethree-dimensional structures can be found at “Tri-gate (Intel)”: J.Kavalieros et al., Symp. VLSI Tech Pg 50, 2006 AND “FinFET: Yamashita etal. (IBM Alliance), VLSI 2011, both incorporated herein by reference intheir entireties. Conventional ion implanters cannot easily dopesidewalls, especially in high aspect ratio structures. Additionally, ina dense array of i3D structures, there can be shadowing effects for thedirectional ion beam in an implanter, giving rise to serious doseretention problems for tilted implant angles. In addition toconventional silicon-based microelectronics, other applications of CFDdoping include microelectronics and optoelectronics based on III-Vsemiconductors such as GaAs and II-VI semiconductors such as HgCdTe,photovoltaics, flat panel displays, and electrochromic technology.

FIG. 16 illustrates a transistor having a three-dimensional gatestructure, in which the source and drain are formed in thin verticalstructures that are difficult to dope by conventional ion implantationtechniques. However, when a thin layer of n or p-doped CFD oxide isformed over the vertical structures conformal doping is accomplished.Conformal doping has been observed to increase current density inthree-dimensional devices by 10-25% due to decreased series resistance.See Yamashita et al, VLSI 2011.

CFD doped oxides as diffusion sources have various advantages. First,they provide high conformality at low temperature. Because the dopingfilm may be sacrificial, a non-conformal film typically faces morechallenges in removal, i.e. some areas can be overetched. As explained,CFD provides highly conformal films. Additionally, CFD providesextremely well controlled doping concentration. A CFD process canprovide one or more layers of undoped oxide followed by a single layerof doping, as needed. The level of doping can be tightly controlled bythe frequency with which the doped layer is deposited and the conditionsof the doping cycle. In certain embodiments, the doping cycle iscontrolled by, for instance using a dopant source with significantsteric hindrance.

FIG. 17 presents a baseline CFD sequence of operations from left toright with advancing time along the x axis. Numerous variations aresupported, and this figure is presented for purposes of illustrationonly. Initially in the sequence, during an operation A, a vapor phaseoxidant is introduced into the reaction chamber that contains thesubstrate onto which the CFD films to be deposited. Examples of suitableoxidants include elemental oxygen (e.g., O₂ or O₃), nitrous oxide (N₂O),water, alkyl alcohols such as isopropanol, carbon monoxide, and carbondioxide. The oxidant is typically provided together with an inert gassuch as argon or nitrogen.

Next, in an operation B, a dielectric precursor is temporarilyintroduced into the reaction chamber. The duration of operation B ischosen to allow the precursor to adsorb onto the substrate surface in anamount sufficient to support one cycle of film growth. In someembodiments, the precursor saturates the substrate surface. Theprecursor will be chosen for its ability to produce a dielectric of thedesired composition. Examples of dielectric compositions include siliconoxides (including silicate glasses), silicon nitrides, siliconoxynitrides, and silicon oxycarbides. Examples of suitable precursorsinclude alkylamino silanes (SiH_(x)(NR₂)_(4−x)) where x=1-3, and Rincludes alkyl groups such as methyl, ethyl, propyl, and butyl invarious isomeric configurations) and halosilanes (SiH_(x)Y_(4−x)) wherex=1-3, and Y includes Cl, Br, and I). More specific examples includebis-alkylamino silanes and sterically hindered alkyl silanes. In onespecific example, BTBAS is a precursor for producing silicon oxide.

During operation B, the oxidant which was introduced into the chamberduring phase A continues to flow. In certain embodiments, it continuesto flow at the same rate and in the same concentration as duringoperation A. At the conclusion of operation B, the flow of dielectricprecursor into the chamber is terminated and an operation C begins asdepicted. During operation C, the oxidant and inert gas continues toflow as during operations A and B to purge the remaining dielectricprecursor in the reaction chamber.

After the purge is completed during operation C, the precursor isreacted on the substrate surface to form a portion of the dielectricfilm (see operation D). In various embodiments, a plasma is applied todrive the reaction of the adsorbed dielectric precursor. In someexamples, this reaction is an oxidation reaction. Some of the oxidantpreviously flowing into the reaction chamber may be adsorbed onto thesurface along with the dielectric precursor, thus providing animmediately available oxidizing agent for the plasma-mediated surfacereaction.

Operations A through D collectively provide a single cycle of thedielectric film deposition process. It should be understood that otherCFD embodiments described herein may be used in place of the basic cycledepicted here. In the depicted embodiment, the deposition cycle (Athrough D) is performed without introduction of any dopant species. Invarious embodiments, the cycle represented by operations A through D isrepeated one or more times in succession prior to introduction of adopant species. This is illustrated in phase E of FIG. 17. In someexamples, operations A-D are repeated at least once, or at least twice,or at least five times, prior to introduction of a dopant.

As an example, the dielectric is deposited at a rate of about 0.5 to 1Angstroms/cycle. Through each of the one or more cycles (repetitions ofA-D), the oxidant continues to flow into the reaction chamber.

At some point in the process, the cycles of dielectric deposition areinterrupted by introduction of a dopant precursor species such as, e.g.,diborane. This is illustrated as an operation F in the figure. Examplesof dopants that may be provided in the dielectric source film includevalence III and IV elements such as boron, gallium, phosphorous,arsenic, and other dopants. Examples of dopant precursors, in additionto diborane, include phosphine and other hydride sources. Non-hydridedopants such as alkyl precursors (e.g. trimethylgallium), haloprecursors(e.g. gallium chloride) can also be used.

In some versions, dopant is deposited at the interface with theunderlying substrate, followed by CFD cycles interspersed with dopantpulses every x number of cycles (as described), and optionally toppedwith an undoped protective “capping” layer may be a CFD oxide film. Seean example of the resulting stack in FIG. 18.

In a specific embodiment, the dopant precursor species is provided tothe reaction chamber in mixture with a carrier gas such as an inert gas(e.g., argon), but not with an oxidant or other reactant. Thus, in thisbaseline example, flow of the oxidant ceases during operation F. Inother embodiments, the precursor is introduced together with a reducingagent or an oxidizing agent. In certain embodiments, the concentrationof dopant to carrier gas between about 1:5 and 1:20. In certainembodiments, the dopant deposition temperature is between about 300 and400° C. The duration of the dopant exposure step varies according to thetargeted dopant concentration. In certain embodiments, the exposure stepis between about 2.5 s and 7.5 s. In a specific example, 1000 sccm ofdiborane is flowed in 10000 sccm of argon at 3 Torr pressure and about400 C.

In certain embodiments, the dopant precursor collects on the substratesurface by a non-surface limited mechanism. For example, the precursormay deposit by CVD-type process rather than an ALD (surface adsorptionlimited) process.

Optionally the dopant precursor is purged from the reaction chamberprior to further processing of the dielectric film. Additionally, asdepicted in the FIG. 17, delivery of the dopant precursor is followed byan optional activation operation G, which may be mediated by plasma,elevated temperature, etc. In the example of diborane as the dopantprecursor, the activation operation converts diborane to elementalboron. After operation G is complete, the process continues with anoptional purge (not shown).

In one example, involving CVD diborane dopant, the activation operationis solely temperature based decomposition to produce boron. This is atemperature sensitive process. At higher temperatures, one may employrelatively short exposure times to target the same boron concentrationper unit thickness. Alternatively, in some processes (e.g., thoseemploying trimethylborane (TMB)), the activation may involve a plasma orthermal oxidation step. For some other precursors, it may be appropriateto employ a “pinning” step to hold the free boron or other dopant inplace. This may be accomplished using a “pinning” plasma.

In certain embodiments, plasma activation involves RF power of anyfrequency suitable for incorporating carbon into the film. In someembodiments, the RF power supply may be configured to control high- andlow-frequency RF power sources independently of one another. Examplelow-frequency RF powers may include, but are not limited to, frequenciesbetween about 200 kHz and 1000 kHz. Example high-frequency RF powers mayinclude, but are not limited to, frequencies between about 10 MHz and 80MHz (e.g., 13.56 MHz). Likewise, RF power supplies and matching networksmay be operated at any suitable power to form plasma. Examples ofsuitable powers include, but are not limited to, powers between about100 W and 3000 W for a high-frequency plasma and powers between about100 W and 10000 W for a low-frequency plasma (on a per wafer basis). TheRF power supply may be operated at any suitable duty cycle. Examples ofsuitable duty cycles include, but are not limited to, duty cycles ofbetween about 5% and 90%. Generally acceptable process pressures arebetween about 0.5-5 Torr and preferably about 2-4 Torr. For certainplasma pretreatments (of the underlying substrate) prior to exposure todopant, pressures up to about 10 Torr (or up to about 9 Torr) have beenfound to work well.

The following table summarizes ranges of plasma parameters that may beused for various BSG processes:

Process Process Plasma power Plasma exposure pressure CFD oxide growthHF: 200 to 2500 W 0.1 to 5 s 0.5-5 Torr Plasma pretreatment HF: 100 to1000 W;  0 to 60 s  2-9 Torr LF: 0 to 1000 W

In the depicted baseline process, the cycles of dielectric depositionand intermittent dopant delivery (operations A through G) may beperformed multiple times as shown in a phase H of the figure. The actualnumber of times that the process sequence is repeated depends upon thedesired total thickness of the film and the thickness of the dielectricdeposited per cycle, as well as the amount of dopant incorporated intothe film. In some embodiments, operations A-G are repeated at leasttwice, or at least three time, or at least five times, or at least aboutten times.

After the dielectric film is completely deposited, it may be used as asource of dopant species for nearby semiconductor structures. This maybe accomplished by driving the dopant from the deposited film into thedevice structure as depicted at an operation I of FIG. 17. In variousembodiments, the driving is accomplished by a thermally mediateddiffusion process such as an anneal. In some cases, particularly thoseemploying ultra-shallow junctions, laser spike annealing may beemployed.

Numerous variations on this baseline process may be realized. Some ofthese variations have as their goal increasing the amount of dopantavailable for diffusion into an adjacent semiconductor structure. Othervariations are designed to control the rate at which the dopant isdelivered from the source film into the nearby semiconductor structure.Still other variations control the direction that the dopant speciesdiffuse. Frequently, it is desirable to favor the diffusion of thedopant toward the device structure and away from the opposite side ofthe film.

In certain embodiments, the frequency with which a dopant is introducedinto a growing dielectric film is controlled. More frequent dopantprecursor delivery cycles result in an overall greater concentration ofdopant in the final dielectric film. They also result in a relativelyeven distribution of dopant throughout the film. When fewer dopantprecursor delivery cycles are inserted into the deposition process, theregions of high dopant concentration in the film are more widelyseparated than is the case when the dopant delivery cycles are morefrequent.

In one embodiment, the dopant precursor is delivered to the growingdielectric film one time for each cycle of dielectric deposition. Inanother embodiment, the dopant precursor is delivered once during everyother cycle of dielectric deposition. In other embodiments, lessfrequent dopant precursor delivery cycles are incorporated in theprocess. For example, the dopant precursor may be delivered once duringevery third, fourth, or fifth cycle of dielectric deposition. In somecases, the dopant precursor is delivered at a frequency of about onceduring every 5-20 dielectric deposition cycles.

It should be understood that the frequency of the dopant precursorintroduction into the growing film need not be consistent over thecourse of the dielectric film deposition. With this in mind, theresulting dielectric film may have a graded composition of dopant suchthat the average concentration of dopant over the thickness of thedeposit dielectric film is non-uniform. In one embodiment, theconcentration of dopant is greater on the side of the dielectric filmthat abuts the semiconductor device structure to be doped. Of course,the dopant concentration gradient in the dielectric film can be tailoredas desired by carefully varying the frequency of dopant delivery cyclesover the course of the entire dielectric deposition process.

Another variation on the baseline process involves adjusting the amountof dopant precursor delivered during any dopant precursor deliverycycle. The amount of dopant precursor delivered during any given dopantdelivery cycle will be determined by the concentration of dopantprecursor delivered to the reaction chamber as well as the duration ofthe exposure of the substrate to be delivered dopant precursor.

As indicated above, some dopant precursors may be provided on to thegrowing film via a CVD-like process. In such cases, the amount of dopantprecursor delivered to the growing film in any given cycle is notlimited by adsorption or other surface-mediated phenomenon. Therefore,the amount of dopant precursor provided during any cycle of dopantdelivery can be relatively large and controllable. To the extent thatgreater amounts of dopant precursor are delivered during any dopantdelivery cycle, the overall concentration of dopant in the dielectricfilm increases. This may offset the effect of having relativelyinfrequent dopant precursor delivery cycles in the overall process.However, it should be understood that increasing the amount of dopantdelivered during any given dopant precursor delivery cycle may result ina relatively high local concentration of dopant in the film. Of course,such dopant concentration spike can be softened by annealing or otheroperation by which the dopant diffuses to make its concentration moreuniform in the dielectric film.

In the case of boron being the dopant, the flux of boron deliveredduring a typical boron precursor delivery cycle may vary from about 7.5ML (Mega-Langmuirs) to 30 ML depending on target film concentration, MLbeing a unit of flux/exposure.

In some embodiments, the amount of dopant precursor delivered in eachprecursor delivery cycle is not constant throughout the growth of thefull dielectric film. Thus, the amount of dopant precursor delivered percycle can be tailored to produce a desired dopant concentration gradientin the dielectric film. For example, it may be desirable to providegreater amounts of dopant precursor in those dopant precursor deliverycycles that occur at locations in the dielectric film that arerelatively close to the semiconductor device feature to be doped. Theresulting concentration gradient has a greater concentration of dopantin regions of the film that abut device structures to be doped.

In some embodiments, the dopant precursor is incorporated onto thesubstrate surface in an adsorption-limited matter. With such precursors,the introduction of dopant into the film proceeds via an ALD-likeprocess (as opposed to a CVD-like manner as described above). Examplesof dopant precursors that attach to the substrate surface by anabsorption-mediated process include trimethyl borane, and other alkylprecursors such as trimethylgallium. Examples of dopant precursors thataccumulate on substrate surface by a CVD-like process include diborane,phosphine, and arsine.

In general, the concentration profile of the dopant in the dielectricfilm can be tailored as appropriate. In one embodiment, the dopantconcentration spikes to a high level at the edge of the film adjacent tothe structure to be doped. In some embodiments, the concentrationincreases and decreases intermittently throughout the film thickness. Inone example, the dopant (e.g., boron) is provided only at the interfacebetween the underlying substrate and the CFD dielectric layer. Thisdopant layer is sometimes referred to as a “spike layer.” In some cases,pulsing the dopant exposure (using for example CVD exposure to a dopantprecursor), rather than employing a single-step increases the withinwafer uniformity of dopant incorporation. In another example, the CFDoxide or other dielectric is interspersed with dopant (e.g., boron indoped BSG). See FIGS. 18 and 19. The interspersed doped dielectric maybe provided with or without a spike layer. In yet another example, anundoped CFD oxide or other dielectric cap that acts as a protectivelayer. Again, see FIGS. 18 and 19.

The dielectric film in which the dopant species reside can itself betailored to affect the diffusion of the dopant species through the filmitself. For example, the film density and/or chemical composition may becontrolled to produce a desired impact on dopant species diffusion. Insome approaches, the entire dielectric thickness possesses the samedensity or composition such that the tailored dopant diffusionproperties are invariant throughout the film thickness. In otherapproaches, the film properties are tailored such that the dopantdiffusion varies across the film thickness. The inventors have foundthat plasma oxidation parameters can be changed to make a CFD oxide lessdense to allow for greater dopant diffusion across it during an anneal,for example.

In certain embodiments, the composition of the dielectric film (or theprocess gas used to form the film) is tailored to influence the dopantdiffusion therein. It has been found, for example, that the ratio ofnitrogen to oxygen in the oxidant process gas delivered to the reactionchamber during the dielectric film deposition cycles influences theability of dopant species to diffuse through the dielectric film. Forexample, a greater amount of nitrogen present in the oxidant gas usedduring formation of the dielectric film results in the dielectric filmhaving a significant resistance to dopant diffusion. By contrast, arelatively greater amount of oxygen present in the gas results in thefilm having a much less resistance to dopant diffusion. The nitrogenpresent in the process gas may be provided by way of nitrogen containingcompounds (e.g., N₂O) or elemental nitrogen, N₂. In various embodiments,the oxidant that flows continuously during the dielectric filmdeposition cycles contains nitrous oxide.

In certain embodiments, the dielectric film is fabricated by initiallyusing an oxidant gas that is high in oxygen content and relatively lowand nitrogen content during the initial growth phases of the dielectricfilm. Later, after the film is partially formed on the substratestructures to be doped, the oxidant gas is changed in composition sothat it is relatively richer in nitrogen. For example, during initialdeposition cycles, the oxidant gas used for the dielectric film maycontain entirely molecular oxygen. In later dielectric depositioncycles, the oxidant gas is modified so that the oxygen is at leastpartially replaced with nitrous oxide. This assumes that the goal is toenhance diffusion in the direction toward the bottom of the film andblock diffusion in the direction toward the top of the film—assuming thedevice structure to be doped is located underneath the dielectric film.The inventors have found that if nitrogen concentration levels aregreater than about 1E20 atoms/cc (measured by, e.g., SIMS), then theblocking effect to boron diffusion is significant. By contrast, atnitrogen concentration levels of about 1E19 atoms/cc or lower, theblocking effect can be effectively eliminated.

From the perspective of the film composition itself, the nitrogencontent in the film may vary from a relatively low level in the portionof the film near the substrate structure to be doped to a relativelyhigher level in the portion located opposite the structure to be doped.

The deposition temperature employed during formation of the dielectricfilm also influences the ability of the dopant atoms to diffuse withinthe film. In general, it has been found that dielectric deposited atrelatively low temperatures by CFD processing generally permitsrelatively high dopant diffusion rates. Examples of the relatively lowtemperatures associated with relatively high dopant diffusion rates aretemperatures in the range of about 300 to 400° C., or more specificallybetween about 350 to 400° C. Of course, these temperature ranges dependupon the choice of dielectric precursor and other deposition parameters.While they may be employed with a number of precursors, they areparticularly appropriate for the use of BTBAS as the dielectricprecursor.

By contrast, dielectric deposited at relatively higher temperaturestends to resist the diffusion of dopant species. Using BTBAS as thedielectric precursor, relatively high temperatures associated withrelatively low dopant diffusion rates are in the range of about 350 to400° C., or more specifically between about 300 to 380° C. Of course,these temperatures may be applied to other precursors. Further, while itis true that higher temperatures in general give denser films thatresist dopant diffusion, one can also control diffusivity and/or densityvia other parameters such as RF exposure time and power during plasmaoxidation. Examples of baseline parameters that may be employed duringCFD oxide growth include (1) high frequency plasma at about 200-2500Watts (for a 300 mm wafer), typically without low frequency plasma, and(2) plasma exposure times in the range of about 0.2 to 1.5 seconds.

In certain embodiments, a relatively low temperature is employed todeposit dielectric film adjacent to the device structure to be doped anda higher temperature is employed to deposit the portion of thedielectric film further away from the structure. In certain embodiments,the temperature employed during deposition of the full dielectric filmis varied, and as well, the nitrogen to oxygen ratio in the oxidant gasis varied during the deposition process. In this manner, the dopantdiffusion properties of the resulting dielectric film can be varied toan exaggerated degree across the thickness of the film.

In various embodiments, the deposition temperature is controlled byheating and/or cooling a pedestal or chuck that holds the substrateduring CFD. Examples of suitable pedestals are described in U.S. patentapplication Ser. No. 12/435,890 (published application no.US-2009-0277472), filed May 5, 2009, and U.S. patent application Ser.No. 13/086,010, filed Apr. 13, 2011, both of which are incorporatedherein by reference in their entireties.

In certain embodiments, the device structure on the substrate surfacethat is to be doped is pretreated prior to deposition of the dielectricfilm or the dopant precursor. In one example, the pretreatment involvesexposure to a plasma such as a reducing plasma. Such treatment may beappropriate when, for example, the substrate features to be dopedcontains silicon. Typically silicon contains a small quantity of nativeoxide which could serve as a barrier to subsequent diffusion of thedopant. In a specific embodiment, the substrate surface is pretreatedwith a reducing plasma such as a hydrogen containing plasma, and thenthe surface is contacted with the dopant precursor, in the vapor phase,prior to the first cycle of dielectric film deposition. The precursormay be delivered to the reaction chamber immediately after the plasmapretreatment is completed. In some examples, the dopant precursor isdiborane. In general, the process depicted in FIG. 17 may be modified sothat a dopant or dopant precursor is delivered to the substrate surfaceprior to the first dielectric deposition cycle.

In various embodiments, a partially formed dielectric film itself ispretreated with a plasma or other activating treatment prior to exposureto the dopant precursor. This serves to enhance the within-waferuniformity by (a) providing thermal uniformity prior to dopant precursorexposure, (b) activate the dielectric surface (e.g., by chemical and/orphysical roughening) to enhance dopant precursor sticking to dielectricsurface.

In certain other embodiments, the chemical condition of the dopantspecies is controlled during the dopant precursor delivery and/oractivation phases of the film deposition process. In some embodiments,the dopant precursor is treated in a manner that “fixes” the dopant inthe dielectric film and thereby limits dopant diffusion until it issubsequently activated by an anneal other such operation. In oneexample, certain dopants are fixed by oxidizing them or their precursorsduring the dopant delivery phase of the dielectric film depositionprocess. In a specific example, diborane is delivered to the reactionchamber in an oxidizing environment to effectively fix the resultingboron-containing material in the dielectric film. Alternatively, thedopant is fixed by delivering precursor to the reaction chamber in aninert or reducing environment and thereafter exposed to oxidizingenvironment while located on the dielectric film. In contrast, treatmentof certain dopant precursors with a reducing agent, without subsequentoxidation, may produce a more mobile dopant in the dielectric film.

After the source layer is formed (or during its formation), the dopantspecies are driven or otherwise incorporated into adjacent structures inthe device being fabricated. In certain embodiments, the dopant speciesare driven by an anneal during or after the conformal dopant source filmis formed. Besides conventional thermal annealing, flash annealing andlaser spike annealing can be used, for example. The time and temperatureof the anneal depends upon various parameters including theconcentration, amount, and type of dopant in the source layer, thecomposition and morphology of the source layer matrix (e.g., an oxideglass), the distance that the dopant species must travel into adjacentdevice structures, the desired concentration of dopant in the devicestructure, and the composition and morphology of the device structure.In certain embodiments, the anneal is performed at a temperature ofbetween about 900 and 1100° C. for about 2 to 30 seconds.

Various apparatus may be designed to deposit the doped dielectric filmsas described here. Generally, the apparatus will contain a processchamber for holding a substrate during deposition of the doped film. Theprocess chamber will include one or more inlets for admitting processgases, including dielectric precursors, oxidants, carrier gases or inertgases, dopant species and the like. In various embodiments, theapparatus will additionally include features for generating a plasmahaving properties suitable for creating the dielectric layer,incorporating dopant into the dielectric layer, treating the dielectriclayer to modify the electrical, optical, mechanical, and/or chemicalproperties of the layer, and driving dopant from the film into thesubstrate. Typically, the apparatus will include a vacuum pump orprovisions for connecting to such pump. Still further, the apparatuswill have a controller or controllers configured or designed forcontrolling the apparatus to accomplish the sequence of doped dielectricdeposition operations described here. The controller may includeinstructions for controlling various features of the apparatus includingthe valving to deliver of process gases and to control pressure, thepower supply for generating plasmas, and the vacuum source. Theinstructions may control the timing and sequence of the variousoperations. In various embodiments, the apparatus may have features asprovided in the Vector™ family of deposition tools available fromNovellus Systems of San Jose, Calif. Other features of suitableapparatus for depositing doped dielectric films are described elsewhereherein.

Doped CFD Film Properties

The dielectric film serving as a source of dopant species will havevarious characteristics. In various embodiments, the film thickness isbetween about 20 and 200 Angstroms. In some cases, such as for front enddoping of source-drain extension regions of three-dimensional transistorstructures, the film thickness is between about 50 and 100 Angstroms.The average concentration of dopant atoms (or other dopant species) inthe dielectric film depends upon various factors including the totalamount of dopant per unit surface area of the film as well as thediffusivity of the dopant atoms in the film and the doping application.In certain embodiments, the concentration of dopant in the film isbetween about 0.01 and 10 percent by weight. In further embodiments, theconcentration of dopant in the film is between about 0.1 to 1 percent byweight. In still further embodiments, the concentration of dopant in thefilm is between about 0.5 to 4 percent by weight. The techniquesdescribed herein permit tuning of dopant concentrations over a widerange, e.g., between about 0.01 and 10 weight percent. For example, ithas been demonstrated that boron concentration can be easily tunedbetween about 0.1 and 4.3 weight percent in CFD dielectric films. Incertain embodiments, 5, 7, 10, and 12 nm CFD films are grown withbetween about 0.1 and 0.5 wt % boron.

The CFD doped dielectric film may be characterized by other properties.For example, the sheet resistance (Rs) of CFD deposited films may varyfrom about 100 to 50000 ohms/square. In some cases, these values areattained after some or all dopant has been driven from the doped CFDlayer. Further junction depths (measured by SIMS for example) producedby driving dopant from a CFD film can be modulated to a level of up toabout 1000 Angstroms as appropriate. Of course, many front end devicesrequire rather shallower junction depths, e.g., in the range of about5-50 A, which are also attainable using CFD films. The actual junctiondepth can be controlled by many factors including, for example,interfacial dopant (e.g., boron) concentration, mobility of dopant intothe substrate (e.g., silicon) from the bulk and interface, and thetemperature and duration of the anneal used to drive in dopants.

CFD Doping Applications

The substrate surface on which the dielectric source layer is formed mayrequire a highly conformal deposition. In certain examples, thedielectric source film conformably coats features having an aspect ratioof between about 1:0.5 and 1:12 (more specifically between about 1:1 and1:8), and have feature widths of no greater than about 60 nm (morespecifically no greater than about 30 nm). Doping using dielectricsource layers of the types described herein will find particularapplication in devices formed according to the 45 nm technology node andbeyond, including the 22 nm technology node, the 16 nm technology node,etc.

Among the device structures that may be doped using a CFD source layerare conventional doped structures such as CMOS sources and drains,source-drain extension regions, capacitor electrodes in memory devices,gate structures, etc. Other structures that may be doped in this mannerare non-planar or three-dimensional structures such as junctions atsource/drain extension regions in gate structures such as those in somethree-dimensional gate structures employed in some devices fabricated atthe 22 nanometer technology node. Some three-dimensional structures canbe found in “Tri-gate (Intel)”: J. Kavalieros et al., Symp. VLSI Tech Pg50, 2006 AND “FinFET: Yamashita et al. (IBM Alliance), VLSI 2011, andreferences therein, previously incorporated by reference.

Doped CFD films have various other applications such as providingetchable layers used at various stages in integrated circuitfabrication. In certain embodiments, the etchable layer is a glass layerhaving tunable wet etching rates, where the etch rate is tunable by thelevel of doping. In other words, the level of doping is chosen toprovide a pre-defined etch rate. In specific embodiments, the etchablelayer is a silicate glass layer containing a dopant such as phosphorus,boron, or combinations thereof.

CFD Doping Examples

CFD Boron-doped silicate glass (BSG) films were prepared and achievednearly 100% step coverage on complex three-dimensional gatearchitectures. Similar results are expected with phosphorus-dopedsilicate glass (PSG). Boron or phosphorus can be driven from such filmsinto the lateral and vertical regions of the source and drain junctionsduring a subsequent anneal step that provides conformal/homogenous underdiffusion of the dopant. FIG. 20 shows a typical deposition block usedto synthesize a CFD BSG/PSG film. The CFD oxide growth cycle includes(a) a saturating dose of the SiO₂ precursor (BTBAS), (b) an inert purgeto flush out remnant precursor species, (c) an oxidative plasma step,and (d) an inert gas purge to remove reaction by-products. Thismechanism ensures that the reaction is self-limiting and promotes theexcellent conformality observed with these films. A boron or phosphorusexposure step is periodically inserted during the CFD oxide growth,followed by a pump and purge sequence, and an optional RF pinning/curestep (e.g., exposure to plasma) if needed. This deposition block isrepeated as many times as required by the target BSG/PSG thickness. SeeFIG. 20.

While the frequency of insertion of boron or phosphorus exposuremodulates the dopant diffusion distance at a given temperature, thelength of exposure controls the total dopant dose. These two powerfulcontrol parameters provide a versatile synthesis scheme to accuratelytune the interface dopant concentration.

In experiments, CFD has demonstrated excellent growth characteristics inBSG films. The CFD BSG process used BTBAS as the silicon source, N₂Oplasma for oxidation and 5% diborane (B₂H₆) in argon for boron doping. Amixture of argon and N₂O was used as the purging gas. A growth rate of˜1 A/cycle was obtained consistent with results on undoped CFD oxide,showing that the inclusion of a boron exposure step did not affect theCFD growth adversely. 250 A-thick CFD BSG films exhibited near-perfectconformality on different test structures as shown by SEM photographs.Step coverage for these films was calculated to be ˜100% on dense andisolated structures (FIG. 21). Step coverage is defined as the quotientof film thickness on the sidewall of a feature divided by film thicknesson the top of the same feature. Table 3 shows the different splits froman initial study to partition out the effects of boron exposure time,frequency of the boron insertion and growth temperature on the finalaverage boron concentration in the film. 25×CFD Ox means that there are25 CFD undoped oxide cycles per boron insertion stage. This sample wasgrown to 500 Angstroms approximately, so the whole sequence was repeatedaround 20 times (given a growth rate of 1 A/cycle for th CFD oxide).SIMS data for these splits, as presented in FIG. 22, show that theaverage boron concentration can be tuned in a range of about 0.5-3.5 wt% boron, which enables customized doping options.

TABLE 3 Label Deposition Conditions CFDS1 400° C./25x CFD Ox + 5 s B₂H₆exposure CFDS2 400° C./25x CFD Ox + 2.5 s B₂H₆ exposure CFDS3 400°C./50x CFD Ox + 5 s B₂H₆ exposure CFDS4 350° C./25x CFD Ox + 5 s B₂H₆exposure

Apparatus

It will be appreciated that any suitable process station may be employedwith one or more of the embodiments described above. For example, FIG.13 schematically shows an embodiment of a CFD process station 1300. Forsimplicity, CFD process station 1300 is depicted as a standalone processstation having a process chamber body 1302 for maintaining alow-pressure environment. However, it will be appreciated that aplurality of CFD process stations 1300 may be included in a commonlow-pressure process tool environment. While the embodiment depicted inFIG. 13 shows one process station, it will be appreciated that, in someembodiments, a plurality of process stations may be included in aprocessing tool. For example, FIG. 14 depicts an embodiment of amulti-station processing tool 2400. Further, it will be appreciatedthat, in some embodiments, one or more hardware parameters of CFDprocess station 1300, including those discussed in detail below, may beadjusted programmatically by one or more computer controllers.

CFD process station 1300 fluidly communicates with reactant deliverysystem 1301 for delivering process gases to a distribution showerhead1306. Reactant delivery system 1301 includes a mixing vessel 1304 forblending and/or conditioning process gases for delivery to showerhead1306. One or more mixing vessel inlet valves 1320 may controlintroduction of process gases to mixing vessel 1304.

Some reactants, like BTBAS, may be stored in liquid form prior tovaporization at and subsequent delivery to the process station. Forexample, the embodiment of FIG. 13 includes a vaporization point 1303for vaporizing liquid reactant to be supplied to mixing vessel 1304. Insome embodiments, vaporization point 1303 may be a heated vaporizer. Thesaturated reactant vapor produced from such vaporizers may condense indownstream delivery piping. Exposure of incompatible gases to thecondensed reactant may create small particles. These small particles mayclog piping, impede valve operation, contaminate substrates, etc. Someapproaches to addressing these issues involve sweeping and/or evacuatingthe delivery piping to remove residual reactant. However, sweeping thedelivery piping may increase process station cycle time, degradingprocess station throughput. Thus, in some embodiments, delivery pipingdownstream of vaporization point 1303 may be heat traced. In someexamples, mixing vessel 1304 may also be heat traced. In onenon-limiting example, piping downstream of vaporization point 1303 hasan increasing temperature profile extending from approximately 100degrees Celsius to approximately 150 degrees Celsius at mixing vessel1304.

In some embodiments, reactant liquid may be vaporized at a liquidinjector. For example, a liquid injector may inject pulses of a liquidreactant into a carrier gas stream upstream of the mixing vessel. In onescenario, a liquid injector may vaporize reactant by flashing the liquidfrom a higher pressure to a lower pressure. In another scenario, aliquid injector may atomize the liquid into dispersed microdroplets thatare subsequently vaporized in a heated delivery pipe. It will beappreciated that smaller droplets may vaporize faster than largerdroplets, reducing a delay between liquid injection and completevaporization. Faster vaporization may reduce a length of pipingdownstream from vaporization point 1303. In one scenario, a liquidinjector may be mounted directly to mixing vessel 1304. In anotherscenario, a liquid injector may be mounted directly to showerhead 1306.

Showerhead 1306 and pedestal 1308 electrically communicate with RF powersupply 1314 and matching network 1316 for powering a plasma. In someembodiments, the plasma energy may be controlled by controlling one ormore of a process station pressure, a gas concentration, an RF sourcepower, an RF source frequency, and a plasma power pulse timing. Forexample, RF power supply 1314 and matching network 1316 may be operatedat any suitable power to form a plasma having a desired composition ofradical species. Examples of suitable powers include, but are notlimited to, powers between 100 W and 5000 W for a 300 mm wafer.Likewise, RF power supply 1314 may provide RF power of any suitablefrequency. In some embodiments, RF power supply 1314 may be configuredto control high- and low-frequency RF power sources independently of oneanother. Example low-frequency RF frequencies may include, but are notlimited to, frequencies between 50 kHz and 500 kHz. Examplehigh-frequency RF frequencies may include, but are not limited to,frequencies between 1.8 MHz and 2.45 GHz. It will be appreciated thatany suitable parameters may be modulated discretely or continuously toprovide plasma energy for the surface reactions. In one non-limitingexample, the plasma power may be intermittently pulsed to reduce ionbombardment with the substrate surface relative to continuously poweredplasmas.

In some embodiments, the plasma may be monitored in-situ by one or moreplasma monitors. In one scenario, plasma power may be monitored by oneor more voltage, current sensors (e.g., VI probes). In another scenario,plasma density and/or process gas concentration may be measured by oneor more optical emission spectroscopy sensors (OES). In someembodiments, one or more plasma parameters may be programmaticallyadjusted based on measurements from such in-situ plasma monitors. Forexample, an OES sensor may be used in a feedback loop for providingprogrammatic control of plasma power. It will be appreciated that, insome embodiments, other monitors may be used to monitor the plasma andother process characteristics. Such monitors may include, but are notlimited to, infrared (IR) monitors, acoustic monitors, and pressuretransducers.

In some embodiments, pedestal 1308 may be temperature controlled viaheater 1310. Further, in some embodiments, pressure control for CFDprocess station 1300 may be provided by butterfly valve 1318. As shownin the embodiment of FIG. 13, butterfly valve 1318 throttles a vacuumprovided by a downstream vacuum pump (not shown). However, in someembodiments, pressure control of process station 1300 may also beadjusted by varying a flow rate of one or more gases introduced to CFDprocess station 1300.

As described above, one or more process stations may be included in amulti-station processing tool. FIG. 14 shows a schematic view of anembodiment of a multi-station processing tool 2400 with an inbound loadlock 2402 and an outbound load lock 2404, either or both of which maycomprise a remote plasma source. A robot 2406, at atmospheric pressure,is configured to move wafers from a cassette loaded through a pod 2408into inbound load lock 2402 via an atmospheric port 2410. A wafer isplaced by the robot 2406 on a pedestal 2412 in the inbound load lock2402, the atmospheric port 2410 is closed, and the load lock is pumpeddown. Where the inbound load lock 2402 comprises a remote plasma source,the wafer may be exposed to a remote plasma treatment in the load lockprior to being introduced into a processing chamber 2414. Further, thewafer also may be heated in the inbound load lock 2402 as well, forexample, to remove moisture and adsorbed gases. Next, a chambertransport port 2416 to processing chamber 2414 is opened, and anotherrobot (not shown) places the wafer into the reactor on a pedestal of afirst station shown in the reactor for processing. While the embodimentdepicted in FIG. 14 includes load locks, it will be appreciated that, insome embodiments, direct entry of a wafer into a process station may beprovided.

The depicted processing chamber 2414 comprises four process stations,numbered from 1 to 4 in the embodiment shown in FIG. 14. Each stationhas a heated pedestal (shown at 2418 for station 1), and gas lineinlets. It will be appreciated that in some embodiments, each processstation may have different or multiple purposes. For example, in someembodiments, a process station may be switchable between a CFD and PECVDprocess mode. Additionally or alternatively, in some embodiments,processing chamber 2414 may include one or more matched pairs of CFD andPECVD process stations. While the depicted processing chamber 2414comprises four stations, it will be understood that a processing chamberaccording to the present disclosure may have any suitable number ofstations. For example, in some embodiments, a processing chamber mayhave five or more stations, while in other embodiments a processingchamber may have three or fewer stations.

FIG. 14 also depicts an embodiment of a wafer handling system 2490 fortransferring wafers within processing chamber 2414. In some embodiments,wafer handling system 2490 may transfer wafers between various processstations and/or between a process station and a load lock. It will beappreciated that any suitable wafer handling system may be employed.Non-limiting examples include wafer carousels and wafer handling robots.FIG. 14 also depicts an embodiment of a system controller 2450 employedto control process conditions and hardware states of process tool 2400.System controller 2450 may include one or more memory devices 2456, oneor more mass storage devices 2454, and one or more processors 2452.Processor 2452 may include a CPU or computer, analog and/or digitalinput/output connections, stepper motor controller boards, etc.

In some embodiments, system controller 2450 controls all of theactivities of process tool 2400. System controller 2450 executes systemcontrol software 2458 stored in mass storage device 2454, loaded intomemory device 2456, and executed on processor 2452. System controlsoftware 2458 may include instructions for controlling the timing,mixture of gases, chamber and/or station pressure, chamber and/orstation temperature, wafer temperature, target power levels, RF powerlevels, substrate pedestal, chuck and/or susceptor position, and otherparameters of a particular process performed by process tool 2400.System control software 2458 may be configured in any suitable way. Forexample, various process tool component subroutines or control objectsmay be written to control operation of the process tool componentsnecessary to carry out various process tool processes. System controlsoftware 2458 may be coded in any suitable computer readable programminglanguage.

In some embodiments, system control software 2458 may includeinput/output control (IOC) sequencing instructions for controlling thevarious parameters described above. For example, each phase of a CFDprocess may include one or more instructions for execution by systemcontroller 2450. The instructions for setting process conditions for aCFD process phase may be included in a corresponding CFD recipe phase.In some embodiments, the CFD recipe phases may be sequentially arranged,so that all instructions for a CFD process phase are executedconcurrently with that process phase.

Other computer software and/or programs stored on mass storage device2454 and/or memory device 2456 associated with system controller 2450may be employed in some embodiments. Examples of programs or sections ofprograms for this purpose include a substrate positioning program, aprocess gas control program, a pressure control program, a heatercontrol program, and a plasma control program.

A substrate positioning program may include program code for processtool components that are used to load the substrate onto pedestal 2418and to control the spacing between the substrate and other parts ofprocess tool 2400.

A process gas control program may include code for controlling gascomposition and flow rates and optionally for flowing gas into one ormore process stations prior to deposition in order to stabilize thepressure in the process station. A pressure control program may includecode for controlling the pressure in the process station by regulating,for example, a throttle valve in the exhaust system of the processstation, a gas flow into the process station, etc.

A heater control program may include code for controlling the current toa heating unit that is used to heat the substrate. Alternatively, theheater control program may control delivery of a heat transfer gas (suchas helium) to the substrate.

A plasma control program may include code for setting RF power levelsapplied to the process electrodes in one or more process stations.

In some embodiments, there may be a user interface associated withsystem controller 2450. The user interface may include a display screen,graphical software displays of the apparatus and/or process conditions,and user input devices such as pointing devices, keyboards, touchscreens, microphones, etc.

In some embodiments, parameters adjusted by system controller 2450 mayrelate to process conditions. Non-limiting examples include process gascomposition and flow rates, temperature, pressure, plasma conditions(such as RF bias power levels), pressure, temperature, etc. Theseparameters may be provided to the user in the form of a recipe, whichmay be entered utilizing the user interface.

Signals for monitoring the process may be provided by analog and/ordigital input connections of system controller 2450 from various processtool sensors. The signals for controlling the process may be output onthe analog and digital output connections of process tool 2400.Non-limiting examples of process tool sensors that may be monitoredinclude mass flow controllers, pressure sensors (such as manometers),thermocouples, etc. Appropriately programmed feedback and controlalgorithms may be used with data from these sensors to maintain processconditions.

System controller 2450 may provide program instructions for implementingthe above-described deposition processes. The program instructions maycontrol a variety of process parameters, such as DC power level, RF biaspower level, pressure, temperature, etc. The instructions may controlthe parameters to operate in-situ deposition of film stacks according tovarious embodiments described herein.

The apparatus/process described hereinabove may be used in conjunctionwith lithographic patterning tools or processes, for example, for thefabrication or manufacture of semiconductor devices, displays, LEDs,photovoltaic panels and the like. Typically, though not necessarily,such tools/processes will be used or conducted together in a commonfabrication facility. Lithographic patterning of a film typicallyincludes some or all of the following operations, each operation enabledwith a number of possible tools: (1) application of photoresist on aworkpiece, i.e., substrate, using a spin-on or spray-on tool; (2) curingof photoresist using a hot plate or furnace or UV curing tool; (3)exposing the photoresist to visible or UV or x-ray light with a toolsuch as a wafer stepper; (4) developing the resist so as to selectivelyremove resist and thereby pattern it using a tool such as a wet bench;(5) transferring the resist pattern into an underlying film or workpieceby using a dry or plasma-assisted etching tool; and (6) removing theresist using a tool such as an RF or microwave plasma resist stripper.

It is to be understood that the configurations and/or approachesdescribed herein are exemplary in nature, and that these specificembodiments or examples are not to be considered in a limiting sense,because numerous variations are possible. The specific routines ormethods described herein may represent one or more of any number ofprocessing strategies. As such, various acts illustrated may beperformed in the sequence illustrated, in other sequences, in parallel,or in some cases omitted. Likewise, the order of the above-describedprocesses may be changed.

The subject matter of the present disclosure includes all novel andnonobvious combinations and subcombinations of the various processes,systems and configurations, and other features, functions, acts, and/orproperties disclosed herein, as well as any and all equivalents thereof.

The invention claimed is:
 1. A method of depositing a film on anon-planar substrate surface in a reaction chamber, the methodcomprising: introducing a first reactant into the reaction chamber undernon-plasma conditions allowing the first reactant to adsorb onto thenon-planar substrate surface; introducing a second reactant into thereaction chamber to react with the adsorbed first reactant; introducinga dopant containing material into the reaction chamber; and forming adoped film conformal to the non-planar substrate surface.
 2. The methodof claim 1, wherein the first reactant is a silicon-containing reactant.3. The method of claim 1, wherein the dopant is selected from the groupconsisting of boron, phosphorous, arsenic, and gallium.
 4. The method ofclaim 1, wherein the second reactant is an oxidant.
 5. The method ofclaim 1, wherein the second reactant is a nitrogen-containing reactant.6. The method of claim 1, wherein the doped film is a doped siliconoxide film.
 7. The method of claim 1, wherein the doped film is a dopedsilicon nitride film.
 8. The method of claim 1, wherein the doped filmis a doped silicon carbide film.
 9. The method of claim 1, wherein aplasma is ignited while the second reactant is in a gas phase in thereaction chamber.
 10. The method of claim 1, wherein the dopant isintroduced to the reaction chamber under non-plasma conditions.
 11. Themethod of claim 1, further comprising exposing the non-planar substratesurface to plasma after introducing the dopant to the reaction chamber.12. The method of claim 1, further comprising repeating one or moretimes the operations of introducing a first reactant into the reactionchamber under non-plasma conditions allowing the first reactant toadsorb onto the non-planar substrate surface and introducing a secondreactant into the reaction chamber to react with the adsorbed firstreactant.
 13. The method of claim 12, further comprising repeating theoperation of introducing a dopant containing material into the reactionchamber one or more times.
 14. The method of claim 13, wherein thedopant containing material is introduced to the reaction chamber at alower frequency than the first reactant is introduced to the reactionchamber.
 15. The method of claim 13, wherein the dopant containingmaterial is introduced to the reaction chamber at the same frequency asthe first reactant is introduced to the reaction chamber.
 16. The methodof claim 1, further comprising exposing the non-planar substrate surfaceto an anneal after introducing the dopant to the reaction chamber.
 17. Amethod of depositing a doped silicon oxide film on a non-planarsubstrate surface in a reaction chamber, the method comprising:introducing a silicon-containing first reactant into the reactionchamber under non-plasma conditions allowing the first reactant toadsorb onto the non-planar substrate surface; introducing an oxidantinto the reaction chamber to react with the adsorbed first reactant; andintroducing a dopant containing material into the reaction chamber toform a doped silicon oxide film conformal to the non-planar substratesurface.
 18. The method of claim 17, wherein a plasma is ignited whilethe oxidant is in a gas phase in the reaction chamber.
 19. A method ofdepositing a doped silicon nitride film on a non-planar substratesurface in a reaction chamber, the method comprising: introducing asilicon-containing first reactant into the reaction chamber undernon-plasma conditions allowing the first reactant to adsorb onto thenon-planar substrate surface; introducing a nitrogen-containing reactantinto the reaction chamber to react with the adsorbed first reactant; andintroducing a dopant containing material into the reaction chamber toform a doped silicon nitride film conformal to the non-planar substratesurface.
 20. The method of claim 19, wherein a plasma is ignited whilethe nitrogen-containing reactant is in a gas phase in the reactionchamber.